JP5098756B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus that reads a document in a main scanning direction by a reading unit while changing a relative position between the reading unit and the document in a sub-scanning direction.

  Conventionally, as an image reading apparatus, a reading unit or a document is conveyed in the sub-scanning direction, and the conveyance target is moved by an amount corresponding to the reading interval while changing the relative position between the reading unit and the document in the sub-scanning direction. By causing the reading unit to perform a reading operation in the main scanning direction, the reading unit generates image data representing the read image of each line, and by combining the image data, image data representing the read image of the entire document is obtained. An image reading apparatus for generating is known.

  Further, the image reading apparatus is provided with an LED (light emitting diode) capable of emitting red light, an LED capable of emitting green light, and an LED capable of emitting blue light as a light source for illuminating a document. Color reading is possible to generate red, green, and blue luminance data by changing the relative position of the reading unit and the document in the sub-scanning direction while sequentially switching the LEDs, and generate color image data as the result of reading the document An image reading apparatus is known (see Patent Document 1).

  For example, in the conventional apparatus, each time the conveyance target moves by a predetermined amount, the LED is turned on for a predetermined time, and the light emitted from the LED is reflected back to the document and arranged in the main scanning direction in the reading unit. The received light receiving element receives light.

  At this time, in the light receiving element, charges corresponding to the amount of received light are accumulated by the photoelectric effect. The reading unit transfers the charge accumulated in each light receiving element in this way as pixel data to the shift register every time the conveyance target moves by a predetermined amount, thereby obtaining luminance data in the main scanning direction according to the accumulated charge amount. Therefore, the luminance data of the lighting color is generated. At the same time, the charge accumulated in the light receiving element is reset, and the next power storage operation is started.

In this way, in the conventional apparatus, every time the conveyance target moves by a predetermined amount, luminance data is generated while switching the lighting color, and color image data is generated.
JP 2007-184907 A

  By the way, in the conventional apparatus, the conveyance target is conveyed at a constant speed, and the luminance data generated during this period is combined to generate image data representing the read image of the entire document. There is a reason to generate

  In this type of image reading apparatus, if the light reception time at the time of generating each luminance data is different due to the combination of the luminance data in the main scanning direction and representing the read image of the entire document, the light reception time in each luminance data is different. Accordingly, the brightness varies accordingly, and the read image of the entire document is uneven.

  For this reason, in the conventional apparatus, the light receiving time of each light receiving operation performed each time the transport target moves by a certain amount is maintained by maintaining the transport target at a constant speed, and the brightness in the main scanning direction is set. The image data of the entire original composed of a combination of data is made uniform.

  However, when the object to be conveyed is conveyed at a constant speed and only the luminance data generated during this period is combined to represent the read image of the entire original, the entire original is read using the reading result during acceleration / deceleration. Since the image cannot be expressed, it is inefficient.

  In addition, in an image reading apparatus of a type that conveys a reading unit, a space for a length required for acceleration / deceleration of the reading unit is added as a space for conveying the reading unit in addition to the length of the original in the sub-scanning direction. There is a problem that the size of the apparatus becomes large by the length necessary for acceleration / deceleration.

  For these reasons, the present inventors have considered expressing the read image of the entire document using the reading result during acceleration / deceleration. However, in the conventional method, if the moving speed of the conveyance target is changed, the light reception time is changed, resulting in luminance variations.

  For example, in the prior art, the periphery of the light receiving element is shielded from the outside so that light does not enter the light receiving element during the non-lighting period of the LED. While keeping the power storage due to, the LED is turned on for a certain period each time the object to be conveyed is conveyed by a certain amount, so that the influence of the light reception time does not affect the reading result. Even in this case, during the non-lighting period of the LED, a slight dark current is generated by the light that slightly enters from the outside, and the luminance changes.

  The influence of this change in brightness due to dark current may be negligible in an environment where the speed of the transport target varies slightly due to an error in motor control, etc., but is ignored in an environment where the speed of the transport target changes greatly. Can not. Further, in order to cope with such a problem, if the light receiving time is made constant, the reading position of each luminance data is not equally spaced in the sub-scanning direction because the conveyance target does not move at a constant speed. Distortion occurs in the entire read image.

  The present invention has been made in view of these problems, and an object of the present invention is to provide a technique capable of finishing image data without unevenness as image data of the entire document while using a reading result during acceleration / deceleration. .

  An image reading apparatus of the present invention made to achieve such an object includes an irradiating means for irradiating light on a document to be read, a reading unit, a signal input means, a conveying means, a taking means, and a measuring means. And a lighting control means.

  In this image reading apparatus, the signal input means periodically inputs a start signal to the reading unit, and the conveying means conveys either the reading unit or the document in the sub-scanning direction as a conveyance target.

  On the other hand, the reading unit includes a light receiving unit for each pixel that receives reflected light or transmitted light of the light irradiated to the document by the irradiation unit along the main scanning direction, and receives the light received by each light receiving unit. A pixel holding unit for storing and holding signal charge information corresponding to the quantity is provided. Each time the start signal is input, the reading unit holds signal charge information representing the reading result of the original accumulated in each light receiving unit during the period until the input as pixel data in the pixel holding unit. Reset each light receiving unit.

  Each time the start signal is input to the reading unit by the signal input unit, the capturing unit uses the pixel data group held in the pixel holding unit by inputting the start signal as image data for one unit representing the reading result. Capture from the pixel holding unit.

Further, the measuring unit is configured to measure the conveyance amount of the conveyance target, and the lighting control unit is based on the measurement result of the measurement unit, and the prescribed amount corresponding to the reading interval in the sub-scanning direction in which the conveyance target is determined in advance. Whenever it is displaced in the sub-scanning direction, the irradiating means is caused to execute the irradiation operation for a predetermined time that is shorter than the output period of the start signal by the signal input means. The measurement means includes a signal generator that generates an edge signal every time the conveyance target is displaced by a predetermined amount in the sub-scanning direction, and updates a measurement value for the conveyance amount of the conveyance target each time the edge signal is generated. Thus, it can be configured as means for measuring the transport amount of the transport target in the sub-scanning direction. The lighting control means is a means for causing the irradiating means to perform an irradiation operation in accordance with the generation of the edge signal. Each time the edge signal is generated, the lighting control means is based on the updated measurement value by the generation of the edge signal. Is determined by a predetermined amount corresponding to a predetermined scanning interval in the sub-scanning direction, whether or not it has been displaced in the sub-scanning direction. From the above, it can be configured as means for causing the irradiation means to perform the irradiation operation for a predetermined time that is shorter than the output period of the start signal by the signal input means.

  In the image reading apparatus configured as described above, as described above, the light receiving time by the reading unit is held constant, the reading unit is caused to repeatedly perform the light receiving operation, and the image for one unit is received for each light receiving operation. While generating data, the light irradiation operation for the original for realizing the light receiving operation is performed every time the conveyance target is displaced by the specified amount. In addition, the irradiation operation is performed only for a predetermined time (specified time) regardless of the moving speed of the conveyance target.

Therefore, according to the present invention, even when the image of the entire document is expressed by combining the image data for one unit in the main scanning direction generated in each light receiving operation, unevenness in luminance does not occur.
Further, since each irradiation operation is executed in accordance with the movement of the original, even if the moving speed of the conveyance target changes, it is possible to express an image of the entire original by combining image data whose reading positions are equally spaced. Therefore, according to the present invention, it is possible to suppress the occurrence of variations in the reading position and the distortion of the entire document image.

Therefore, according to the present invention, uniform image data can be finished as image data of the entire document while using the reading result during acceleration / deceleration.
However, if the light receiving operation and the irradiation operation are performed asynchronously in this way, there is a possibility that the irradiation operation is performed with the charge resetting operation interposed therebetween. Therefore, in the above-described image reading apparatus, the first timing, which is the timing at which the lighting control unit is scheduled to start the irradiation operation by the next irradiation unit, is greater than the second timing, which is the timing at which the next start signal is input to the reading unit. It is preferable to provide a determination means for executing the determination as to whether or not the time is before the predetermined margin amount before the specified time of the second timing.

  The image reading apparatus prohibits execution of an irradiation operation scheduled to be executed at the first timing when the determination unit determines that the first timing is before the second timing. In place of the irradiation operation for which the execution is prohibited, the irradiation means starts the irradiation operation for the specified time at any time from the time when the determination is made by the determination means to the time before the predetermined time of the second timing. It is preferable to provide lighting control means.

  In this way, if the image reading apparatus is configured, it is possible to prevent the irradiation unit from starting the irradiation operation even though the reset operation is performed in the middle, and a position close to the prohibited irradiation operation. Thus, the irradiating unit can execute an alternative irradiation operation, and even during acceleration / deceleration, the reading unit can appropriately read the original, and image data without unevenness can be finished as image data of the entire original. .

  Immediately after the start signal is input, the signal charge information is transferred from the light receiving unit to the pixel holding unit, and the operation of resetting the charge is performed in the reading unit. Therefore, the irradiation operation is started simultaneously with the input of the start signal. Is not preferred. For this reason, it is preferable that a certain period of time from the input time of the start signal is set as a prohibition period in which the irradiation operation by the irradiation unit is prohibited. In this case, the irradiation operation is performed when the transport target is displaced by a specified amount. In some cases, it cannot be executed.

  Accordingly, the image reading apparatus prohibits the lighting control unit from causing the irradiation unit to perform the irradiation operation during the prohibition period, and replaces the prohibited irradiation operation with the irradiation unit when the prohibition period has elapsed. It is preferable to provide a delayed lighting control means for starting the irradiation operation for a specified time.

  If the image reading apparatus is configured in this manner, the irradiation operation can be executed at an appropriate time while avoiding the irradiation operation immediately after the start signal is input, and the original can be appropriately applied to the reading unit even during acceleration / deceleration. It is possible to read and complete image data without unevenness as image data of the entire document.

In addition, the lighting control unit is configured to cause the irradiation unit to execute the irradiation operation for the specified time each time the conveyance target reaches the lighting start position set at equal intervals at a distance interval corresponding to the predetermined amount in advance. The configuration in which the irradiation unit performs the irradiation operation for the specified time each time the transfer target is displaced in the sub-scanning direction from the position of the transfer target at the time when the irradiation unit started the irradiation operation last time. It is more preferable when it is made.
Specifically, the lighting control unit prohibits execution of the irradiation operation by the forward lighting control unit, and instead of the prohibited irradiation operation, any one from the time when the determination is made by the determination unit to a predetermined time before the second timing. If the irradiation unit starts the irradiation operation for a specified time at such time, the transfer target is displaced in the sub-scanning direction by a specified amount from the position of the transfer target at the time when the irradiation unit starts the irradiation operation. The irradiation unit can be configured to execute the irradiation operation for a specified time.
In addition to this, when the delayed lighting control unit causes the irradiation unit to start the irradiation operation for the specified time when the prohibition period has elapsed, the lighting control unit is to be transported when the irradiation unit starts the irradiation operation. From this position, each time the object to be transported is displaced in the sub-scanning direction by a specified amount, the irradiation means can execute the irradiation operation for a specified time.

  In an image reading apparatus equipped with a forward lighting control means and a delayed lighting control means, the irradiation operation is more equally spaced when the next lighting start position is determined based on the position where the previous lighting was started, rather than the lighting start position being determined in advance. Therefore, it is possible to suppress the occurrence of image distortion when an image of the entire document is expressed.

  Further, the output cycle of the start signal can be set to a time during which the conveyance target is conveyed by a specified amount when the conveyance target is conveyed at a constant speed. If you try to construct image data for the entire document using the reading results at the time of acceleration until shifting to high-speed conveyance and at the time of deceleration after stopping constant-speed conveyance, the speed difference of the conveyance target with respect to constant-speed conveyance is large. In this case, when the start signal is input to the reading unit, there is a case where the irradiation operation by the irradiation unit is not performed at all from the input time of the previous start signal.

  Therefore, in the image reading apparatus described above, the image including information on the signal charges accumulated in the light receiving unit during the period when the irradiation operation by the irradiation unit is executed among the respective image data acquired by the acquisition unit from the reading unit. Data output means for selectively outputting data to the outside may be provided.

  If the image reading apparatus is configured in this manner, even if unnecessary image data including only noise that does not represent the reading result is captured by the capturing unit, it can be eliminated, and subsequent processing becomes complicated. No need.

Embodiments of the present invention will be described below with reference to the drawings.
(1) Overall Configuration of Image Reading Apparatus 1 FIG. 1 is a block diagram showing an electrical configuration of the image reading apparatus 1 to which the present invention is applied. The image reading apparatus 1 according to the present embodiment includes a CPU 11 that executes various arithmetic processes, a ROM 12 that stores various programs and data, and a RAM 13 that is used as a work area when the CPU 11 performs calculations. Execute to control the entire device and realize the scanner function.

  The image reading apparatus 1 further includes a CIS line sensor 20 capable of color reading, a reading control unit 21 that controls the CIS line sensor 20, a drive control unit 17 that controls the motors MT1 and MT2, and encoders EN1 and EN2. The encoder processing unit 15 that executes processing based on the input signal and an external interface 23 are configured to be communicable with an external device (such as a personal computer (PC)) via the external interface 23. Examples of the external interface 23 include a LAN interface and a USB interface.

As shown in FIG. 6, the CIS line sensor 20 includes a light receiving element group 201, a shift register 203, and a plurality of LEDs 20R, 20G, and 20B arranged in a line.
The CIS line sensor 20 includes the light receiving element for each pixel, and each time a line start signal is input, the signal charge accumulated by the light receiving element is input to the shift register 203 as pixel data, and the next line start signal is input. Pixel data is sequentially output from the output terminal of the shift register 203 in accordance with the transfer clock signal during a period until the signal is input.

The LED 20R is an LED that can emit red light, the LED 20G is an LED that can emit green light, and the LED 20B is an LED that can emit blue light.
The image reading apparatus 1 according to the present embodiment is configured to represent a color image with each luminance of the three primary colors of red (R), green (G), and blue (B), and the CIS line sensor 20 reads the color image. According to the LED control signal input from the control unit 21, only one of the LEDs 20R, 20G, and 20B is selectively lit. Then, the light emitted from the LED is reflected by the original and returned by the light receiving element group 201, and each light receiving element receives a signal charge corresponding to the amount of received reflected light representing the reading result of the lighting color. Accumulate.

  Then, the CIS line sensor 20 inputs the signal charge accumulated when the lighting color is red as red line configuration data to the shift register 203, and uses the signal charge accumulated when the lighting color is green as the green line configuration. The signal charge input to the shift register 203 as data and accumulated when the lighting color is blue is input to the shift register 203 as blue line configuration data.

  On the other hand, the reading control unit 21 inputs the line start signal, the transfer clock signal, and the LED control signal to the CIS line sensor 20, and controls the CIS line sensor 20. The reading control unit 21 controls the CIS line sensor 20 for each line and The original is read for each of the three primary colors. Then, the reading control unit 21 writes the line configuration data of each line and each color output as a reading result from the CIS line sensor 20 to the RAM 13 through the memory controller 63.

  The CIS line sensor 20 is fixed at a predetermined reading point when the automatic conveyance reading function is activated, and passes through the reading point by the operation of the ADF device 150 (see FIG. 2) under the control of the reading control unit 21. Scan the document. In addition, the CIS line sensor 20 receives the rotational force of the reading motor MT1 controlled by the drive control unit 17 through the carriage 106 when the stationary document reading function is activated, and below the platen 102A on which the document is placed. The image is moved along the platen 102A in the image reading direction (sub-scanning direction), and at the same time, the document is read line by line and color.

  More specifically, as shown in FIG. 2, an image reading window (hereinafter referred to as a stationary reading window) 102 for a stationary document reading function 102 and an image for an automatic conveyance reading function are provided in the casing of the image reading apparatus 1. A reading window (hereinafter referred to as an automatic reading window) 103 is provided. Both reading windows 102 and 103 are closed by transparent platens 102A and 103A such as glass and acrylic. FIG. 2 is a cross-sectional view showing a mechanical configuration of the image reading apparatus 1.

  In the image reading apparatus 1, a document cover 104 that covers both the reading windows 102 and 103 is assembled on the upper surface side of the apparatus main body 101 so as to be openable and closable. First, the document cover 104 is manually opened by the user, and the document to be read is placed on the stationary reading window 102.

  On the other hand, inside the apparatus main body 101, the CIS line sensor 20 described above receives light reflected from the original and reflected directly under the two reading windows 102 and 103, and generates pixel data based on the received light. However, the CIS line sensor 20 has a longitudinal direction (in other words, a light receiving element arrangement direction) in a main scanning direction perpendicular to the sub-scanning direction which is the moving direction of the CIS line sensor 20. It extends.

  Specifically, the CIS line sensor 20 is assembled so as to be movable in the longitudinal direction of the apparatus main body 101 (the left-right direction in FIG. 2) via the carriage 106, and the automatic reading window 103 is activated when the automatic conveyance reading function is activated. It is placed immediately below. On the other hand, when the stationary document reading function is activated, it moves at a constant speed under the control of the drive control unit 17 immediately below the stationary reading window 102.

  In this embodiment, the carriage 106 is connected to a belt 109 that is hung on a driving pulley 107 and a driven pulley 108, and a reading motor MT1 constituted by a DC motor is connected to the belt 109 via a gear. It is connected.

  That is, when the stationary document reading function is activated, the CIS line sensor 20 receives the rotational force of the reading motor MT1 through the belt 109 and is guided by the guide shaft 111 installed in parallel with the belt 109, while the apparatus main body 101. Is moved straight in the longitudinal direction (sub-scanning direction). FIG. 3 is an explanatory diagram illustrating a movement mode of the CIS line sensor 20.

  Further, the image reading apparatus 1 is configured such that when the reading motor MT1 rotates by a predetermined angle, the CIS line sensor 20 moves by a predetermined distance. In this embodiment, the A-phase signal input from the reading encoder EN1 and Based on the B phase signal, the encoder processing unit 15 detects the position and moving speed of the CIS line sensor 20 and detects the moving direction (forward / reverse direction) of the CIS line sensor 20.

  The image reading apparatus 1 controls the reading motor MT1 by the drive control unit 17 based on the detection result, and moves the CIS line sensor 20 along the guide shaft 111 at a constant speed, while reading control unit 21. Then, the CIS line sensor 20 is controlled to realize a still image reading function.

  Here, a rotary encoder or a linear encoder can be adopted as the reading encoder EN1. When a rotary encoder is adopted as the reading encoder EN1, the reading encoder EN1 is provided on the rotating shaft of the reading motor MT1, and a pulse signal (A phase signal, B phase signal) is output every time the reading motor MT1 rotates by a predetermined angle. Is output from the reading encoder EN1.

  In addition, an ADF device 150 that conveys a document to be read to the automatic reading window 103 is provided in a portion corresponding to the automatic reading window 103 in the document cover 104, and is placed on the document tray 165 by the user when the automatic conveyance reading function is activated. The stacked documents are separated and conveyed to an automatic reading window 103 which is a reading point.

  The ADF device 150 serves as a separation mechanism that separates the stacked originals one by one, a separation roller 153 that abuts on the original placed on the uppermost layer and applies a conveying force to the original, and a separation roller 153 The separation pad 154 that contacts the document from the opposite side of the separation roller 153 and applies a predetermined conveyance resistance, and the suction that sends the document to the separation roller 153 so as to suck the document stacked on the document tray 165 A roller 155.

  In addition, the ADF apparatus 150 turns the direction of conveyance of the document separated and conveyed from the separation mechanism toward the automatic reading window 103 as a conveyance mechanism that conveys the document separated by the separation mechanism to the automatic reading window 103. A paper feed roller 159 that applies a conveying force while being provided, a pair of pinch rollers 160 that press the document against the paper feed roller 159, a document press 161, a paper discharge roller 162, and a document sensor actuator 164 are provided.

  Each roller constituting the ADF device 150 rotates by receiving the rotational force of the reading and conveying motor MT2, and applies a force in the sub-scanning direction to the document contacting the roller, thereby discharging the document from the document tray 165. In the image reading apparatus 1, when the reading and conveying motor MT2 rotates by a predetermined angle, the document to be read moves by a predetermined distance in the sub-scanning direction.

  The document presser 161 presses the conveyed document toward the automatic reading window 103 side. The CIS line sensor 20 reads a document passing through this point while being arranged below the document presser 161 when the automatic conveyance reading function is activated.

  In addition, the document sensor actuator 164 is arranged upstream of the document presser 161 and detects whether or not the document has passed. That is, in this embodiment, the encoder processing is performed based on the ON / OFF signal from the document sensor actuator 164 and the pulse signal from the reading / transporting encoder EN2 installed on the rotation shaft of the reading / transporting motor MT2 formed of a DC motor. The unit 15 detects the document transport position. The reading / transporting encoder EN2 is a rotary encoder that outputs a pulse signal (A phase signal, B phase signal) every time the reading / transporting motor MT2 rotates by a predetermined angle.

  Then, the image reading apparatus 1 controls the conveyance of the document by the drive control unit 17 based on the detection result, conveys the document to the reading point at a constant speed, and the CIS line sensor by the reading control unit 21. 20 is controlled to realize an automatic conveyance reading function.

  The stationary document reading function is such that when a document is not placed on the document tray 165, a reading key (not shown) provided in the image reading apparatus 1 is pressed or a reading command is issued through the external interface 23. Operates when entered. With this operation, the image reading apparatus 1 reads the document placed on the stationary reading window 102.

On the other hand, the automatic conveyance reading function operates when a reading key is pressed or a reading command is input through the external interface 23 in a state where a document is placed on the document tray 165. In the image reading apparatus 1, the automatic conveyance reading function is repeatedly operated until each document placed on the document tray 165 becomes empty, and each document placed on the document tray 165 is sequentially read. Whether a document is not placed on the document tray 165 is determined based on a detection signal of a sensor (not shown) provided on the document tray 165.
(2) Configuration of Encoder Processing Unit 15 and Drive Control Unit 17 Subsequently, the configuration of the encoder processing unit 15 and the drive control unit 17 will be described. FIG. 4 is a block diagram illustrating the configuration of the encoder processing unit 15 and the drive control unit 17.
(2.1) Configuration of Encoder Processing Unit 15 The encoder processing unit 15 includes a set of an encoder edge detection unit 31, a position detection unit 33, and a speed detection unit 35 for each of the encoders EN1 and EN2. The position and speed of the conveyance target (CIS line sensor 20 or document) are detected by the set. When the encoder is a rotary encoder, the position and speed of the conveyance target are indirectly detected by detecting the rotation amount and rotation speed of the motor based on the input signal from the encoder.

  Specifically, the encoder edge detection unit 31 detects the rising edge and the falling edge of the A-phase signal and the B-phase signal input from the corresponding encoders EN1 and EN2, and generates an edge detection signal for each detection of this edge. It is configured to output. This edge detection signal is input to the corresponding position detection unit 33 and speed detection unit 35.

  Furthermore, the encoder edge detection unit 31 detects the moving direction (forward / reverse direction) of the conveyance target based on the phase difference between the A-phase signal and the B-phase signal input from the encoders EN1 and EN2, and the detection result is obtained. The edge detection signal is input to the corresponding position detection unit 33 and speed detection unit 35 together with the edge detection signal.

  The edge detection signal output from the encoder edge detection unit 31 for the read encoder EN1 to which the output signal of the read encoder EN1 is input is input to the position detection unit 33 and the speed detection unit 35 for the read encoder EN1. When the stationary document reading function is activated, the reading is input to the reading front end 41 and the drive stop command generating unit 49 included in the reading control unit 21.

  Further, the edge detection signal output from the encoder edge detector 31 for the read / carry encoder EN2 to which the output signal of the read / carry encoder EN2 is input is input to the position detector 33 and the speed detector 35 for the read / carry encoder EN2. At the same time, when the automatic conveyance reading function is activated, it is input to the reading front end 41 and the drive stop command generating unit 49 provided in the reading control unit 21.

  Further, when the image reading apparatus 1 is turned on, the position detection unit 33 outputs information on the position to be transported enc_pos output from the position detection unit 33 every time an edge detection signal is input from the encoder edge detection unit 31. It is updated by adding one or subtracting one.

  Specifically, based on the information on the movement direction of the conveyance target input together with the edge detection signal, when the conveyance target is moving in the forward direction, the value enc_pos is incremented by 1 (enc_pos ← enc_pos + 1), and the conveyance is performed. If the object is moving in the reverse direction, the value enc_pos is decremented by 1 (enc_pos ← enc_pos−1) and updated.

  The position detection unit 33 for the reading encoder EN1 resets the value enc_pos to zero on condition that the conveyance target (CIS line sensor 20) is arranged at a predetermined origin position (home position). On the other hand, the position detection unit 33 for the reading and transport encoder EN2 resets the value enc_pos to zero when the document sensor actuator 164 detects the leading edge of the document. As a result, the position detecting unit 33 for the reading encoder EN1 detects the position of the CIS line sensor 20, and the position detecting unit 33 for the reading and conveying encoder EN2 detects the conveyance position of the document.

  Further, when the image reading device 1 is turned on, the speed detection unit 35 outputs the output from the speed detection unit 35 based on the edge detection signal every time an edge detection signal is input from the encoder edge detection unit 31. Information on the target speed enc_vel is updated.

  Specifically, the speed enc_vel of the conveyance target is calculated from the reciprocal of the input time interval of the edge detection signal (the time interval between the time when the current edge detection signal is input and the time when the previous edge detection signal is input), Output this.

  The value enc_pos output from the position detection unit 33 for the reading encoder EN1 is input to the drive control unit 17 and to the reading front end 41 included in the reading control unit 21 when the stationary document reading function is activated. The value enc_vel output from the speed detection unit 35 for the reading encoder EN1 is input to the drive control unit 17.

The value enc_pos output from the position detection unit 33 for the reading and transport encoder EN2 is input to the drive control unit 17 and input to the reading front end 41 included in the reading control unit 21 when the automatic transport reading function is activated. Then, the value enc_vel output from the speed detection unit 35 for the reading and transport encoder EN2 is input to the drive control unit 17.
(2.2) Configuration of Drive Control Unit 17 Next, the configuration of the drive control unit 17 will be described. The drive control unit 17 includes a motor control unit 39 that drives the reading motor MT1 and the reading conveyance motor MT2 via a drive circuit 37 (see FIG. 4). The motor control unit 39 controls the motors MT1 and MT2 to be controlled based on the input values enc_pos and enc_vel from the position detection unit 33 and the speed detection unit 35 corresponding to the control target motor.

  More specifically, the motor control unit 39 controls the reading motor MT1 based on the input values enc_pos and enc_vel from the position detection unit 33 and the speed detection unit 35 for the reading encoder EN1 included in the encoder processing unit 15, and also performs reading. Based on the input values enc_pos, enc_vel from the position detector 33 and the speed detector 35 for the transport encoder EN2, the reading transport motor MT2 is controlled.

  Specifically, when the reading function is activated, the motor control unit 39 receives a command from the CPU 11, selects one of the reading motor MT1 and the reading transport motor MT2 as a control target, and controls the selected control target. Therefore, the process shown in FIG. 5 is started. When the stationary document reading function is operated, the reading motor MT1 is selected as a control target, and when the automatic document reading function is operated, the reading conveyance motor MT2 is selected as a control target.

  In addition, when the process shown in FIG. 5 is completed based on the motor drive stop command signal (mtstop) before the reading for all lines is completed, the motor control unit 39 receives a reading restart command from the CPU 11. For the limited time, the process shown in FIG. 5 is started again.

FIG. 5 is a flowchart showing processing executed by the motor control unit 39.
When the process shown in FIG. 5 is started, the motor control unit 39 performs motor drive setting, sets the motor rotation direction to the forward direction (image reading direction), and sets the target conveyance speed Vr according to an instruction from the CPU 11. (S110).

  When this processing is completed, the motor control unit 39 controls the motor to be controlled based on the input signals (enc_pos, enc_vel) from the encoder processing unit 15 according to the content of the drive setting performed in S110 ahead of time. (S120). Specifically, in S120, the motor is controlled so that the transport target is accelerated until the transport speed of the transport target reaches the set target transport speed Vr, and then the transport target is moved regardless of the transport load. The motor is controlled so that the speed becomes constant at the target transport speed Vr. In this embodiment, in this way, the conveyance target is moved in the image reading direction at a constant speed after acceleration.

  Further, during the execution of the control, it is determined whether or not a reading end signal (details will be described later) is input (S130). If the reading end signal is not input (No in S130), the driving is stopped. It is determined whether or not the motor drive stop command signal (mtstop) input from the command generator 49 is a value 1 (S140). If the reading end signal is not input (No in S130) and the motor drive stop command signal is not 1 (No in S140), the motor is controlled while making the determination in S130 and S140. Run continuously.

  When the motor drive stop command signal (mtstop) is switched to the value 1, the motor control unit 39 performs a process of decelerating and stopping the motor to be controlled (S150). After that, when the motor stops, it pauses.

  On the other hand, when the reading end signal is input (Yes in S130), the motor control unit 39 determines whether or not the operating reading function is a stationary document reading function (S160). If the function is a stationary document reading function (Yes in S160), a process of decelerating and stopping the motor to be controlled is performed (S170), and after the motor has stopped, the motor drive setting is performed and the motor rotation direction is set. Is set in the direction opposite to the image reading direction (S180).

  When this process is completed, the motor control unit 39 drives the motor to be controlled (reading motor MT1) and transports the transport target (CIS line sensor 20) to the home position (S185). Then, when the CIS line sensor 20 is transported to the home position, it temporarily stops. Note that the home position of the CIS line sensor 20 is set to a fixed position of the CIS line sensor 20 when the automatic document reading function is activated.

In addition, when the reading function in operation is the automatic conveyance reading function (No in S160), the motor control unit 39 discharges the motor to be controlled (the reading conveyance motor MT2), and the document being conveyed is discharged to the discharge tray 166. (S190). When the document is completely discharged, the motor stops rotating and pauses.
(3) Configuration of Reading Control Unit 21 Subsequently, the configuration of the reading control unit 21 will be described. FIG. 6 is a block diagram illustrating the configuration of the reading control unit 21.

As shown in FIG. 6, the reading control unit 21 includes a reading front end 41, an image data processing unit 43, a local RAM 45, and a drive stop command generation unit 49.
(3.1) Configuration of Reading Front End 41 The reading front end 41 included in the reading control unit 21 is connected to the CIS line sensor 20 and inputs a control signal to the CIS line sensor 20 and is input from the CIS line sensor 20. The pixel data as the read result is received and processed.

The reading front end 41 includes a line start trigger signal generation unit 41a, a line start signal generation unit 41b, an LED control signal generation unit 41c, a transfer clock signal generation unit 41d, and an output control unit 41e. The unit 41a periodically generates a line start trigger (l_start_trg) signal, and inputs a line start signal for designating reading timing to the CIS line sensor 20 based on the line start trigger signal.
(3.1.1) Configuration of Line Start Trigger Signal Generation Unit 41a As described above, the line start trigger signal generation unit 41a periodically generates a line start trigger signal, and uses this line start trigger signal as a line start trigger signal. The signals are input to the signal generator 41b, the LED control signal generator 41c, the transfer clock signal generator 41d, and the output controller 41e.

  The line start trigger signal is a signal that defines the output timing of the line start signal, and is generated at the same cycle as the input cycle of the line start signal to be input to the CIS line sensor 20, and is input to the line start signal generation unit 41b. The In this embodiment, it is assumed that the input period of the line start signal is set at time T0.

  Specifically, when the reading function is activated, the line start trigger signal generation unit 41a starts outputting the line start trigger signal when the conveyance target reaches the reading start position start_pos, and thereafter periodically starts the line start. Outputs a trigger signal.

  The reading start position start_pos is set in advance in the register RG1 included in the reading control unit 21 by the operation of the CPU 11, and the line start trigger signal generation unit 41a has a conveyance target at the reading start position start_pos set in the register RG1. Whether or not it has been reached is determined based on the input value enc_pos from the position detector 33.

  That is, when the reading function is activated, the line start trigger signal generation unit 41a receives information on the value enc_pos updated by the position detection unit 33 from the position detection unit 33 every time an edge detection signal is input from the encoder edge detection unit 31. At the same time, the value enc_pos is compared with the previous value to determine whether the value enc_pos has been switched from less than the value start_pos to the value start_pos. When the value enc_pos is switched from less than the value start_pos to the value start_pos, output of the line start trigger signal is started.

Further, the line start trigger signal generation unit 41a stops outputting the line start trigger signal when reading of all lines is completed.
(3.1.2) Configuration of Line Start Signal Generation Unit 41b The line start signal generation unit 41b provided in the reading front end 41 has a prescribed pulse width suitable for the CIS line sensor 20 at the input timing of the line start trigger signal. A line start signal is generated and input to the CIS line sensor 20 (see FIG. 7B).

When this line start signal is input, in the CIS line sensor 20, the signal charge accumulated in the light receiving element is input to the shift register 203 as pixel data, and is accumulated in the light receiving element before the input of the line start signal. Pixel data representing the reading result of the previous cycle corresponding to the signal charge is stored and held in the shift register 203. At this timing, the signal charge is reset in the light receiving element, and a new reading operation using the photoelectric effect is performed.
(3.1.3) Configuration of LED Control Signal Generating Unit 41c The LED control signal generating unit 41c inputs the LED control signal to the CIS line sensor 20, whereby the LEDs 20R, 20G, and the CIS line sensor 20 have. The lighting of 20B is controlled.

  As described above, the CIS line sensor 20 is configured to reset the light receiving element each time a line start signal is input, performs a light receiving operation for a time corresponding to the input period T0 of the line start signal, and is accumulated during that time. Line configuration data corresponding to the received signal charges is generated.

  However, in the image reading apparatus 1 according to the present embodiment, when any of the LEDs 20R, 20G, and 20B is not lit, the original is not irradiated with light except for background light that slightly enters from the outside. For this reason, when none of the LEDs 20R, 20G, and 20B is lit, the light receiving operation is not substantially realized.

From such a device configuration, the LED control signal generation unit 41c functions as a unit that controls a substantial reading operation of the CIS line sensor 20.
The LED control signal generation unit 41c corresponds to a predetermined 1/3 (one third) line by executing the LED lighting control process (see FIG. 10) described in detail in section (4). Each time the distance and the conveyance target move in the image reading direction, the LED is lit for a predetermined time TE.

  Further, the LED control signal generation unit 41c performs control to switch the LED to be lit from red to green, from green to blue, and from blue to red every time the conveyance target moves in the image reading direction by a distance corresponding to 1/3 line. I do.

  That is, in this embodiment, an area in the sub-scanning direction corresponding to one line is divided into three parts, and the original is read while switching the color of the LED to be lit, so that one line of image data (ie, line data). As described above, color image data including a combination of red line configuration data, green line configuration data, and blue line configuration data is generated.

In this embodiment, the LED lighting time TE is set to a time sufficiently shorter than the input period T0 of the line start signal.
In addition, the LED control signal generation unit 41 c includes a time measurement unit 50 that measures an elapsed time T <b> 1 from when the line start signal is input to the CIS line sensor 20 in order to realize lighting control unique to the image reading apparatus 1. Prepare.

  FIG. 7A is a block diagram showing the time measuring unit 50 provided in the LED control signal generating unit 41c, and FIG. 7B is a time chart showing a mode of time measurement by the time measuring unit 50.

  The time measuring unit 50 is triggered by the input of the line start trigger signal input from the line start trigger signal generation unit 41a at the same time as the time when the line start signal is input to the CIS line sensor 20. The elapsed time T1 is measured every time a line start trigger signal is input.

In this embodiment, since the input period of the line start trigger signal and the line start signal is constant at time T0, the next line start signal is determined from the relationship between the elapsed time T1 and time T0 measured by the time measuring unit 50. The remaining time T2 until it is input to the CIS line sensor 20 can be derived. The LED control signal generation unit 41c derives the remaining time T2 based on such a principle, and performs LED lighting control based on the derived remaining time T2. This will be described in detail in section (4).
(3.1.4) Configuration of Transfer Clock Signal Generation Unit 41d The transfer clock signal generation unit 41d outputs a transfer clock signal for causing the shift register 203 to output pixel data every time a line start trigger signal is input. This is input to the line sensor 20.

  In response to the input of the transfer clock signal, the pixel data (line configuration data) stored in the shift register 203 is output from the shift register 203 in a period until the next line start signal is input.

The line configuration data input from the shift register 203 to the reading front end 41 is transferred to the image data processing unit 43 through the output control unit 41e. It should be noted that the line configuration data input from the CIS line sensor 20 is not shown (not shown) in the reading front end 41 in the path from the reading front end 41 to the image data processing unit 43. The converter converts the analog data into digital data.
(3.1.5) Configuration of Output Control Unit 41e The output control unit 41e sends line configuration data satisfying a predetermined condition among the line configuration data input from the CIS line sensor 20 to the image data processing unit 43. The line configuration data that does not satisfy the condition is selectively transferred and discarded without being transferred to the image data processing unit 43. Specifically, the output control unit 41e selectively transfers only the line configuration data satisfying the predetermined condition to the image data processing unit 43 by executing the output control process shown in FIG.

  In the conventional apparatus, the reading operation is executed only when the conveyance target is moving at a constant speed. However, in the image reading apparatus 1 of the present embodiment, the output is output from the CIS line sensor 20 during acceleration / deceleration of the conveyance target. This line configuration data is also adopted as a document reading result and output to the RAM 13. At this time, the output control unit 41e performs selection of line configuration data to be output to the RAM 13.

  That is, the input period T0 of the line start signal input to the CIS line sensor 20 affects the light receiving time in the light receiving element, and cannot be changed during acceleration / deceleration of the conveyance target.

  On the other hand, if the CIS line sensor 20 executes a reading operation during acceleration / deceleration while keeping the input period of the line start signal constant, the movement of the conveyance target cannot be synchronized with the input of the line start signal. Even when the conveyance target is located at the reading position, the CIS line sensor 20 performs the reading operation.

Therefore, in this embodiment, by executing the output control process shown in FIG. 13, the line configuration data generated by the reading operation performed by the CIS line sensor 20 is selectively displayed in the vicinity of the legitimate reading position. Input to the data processing unit 43. Details of the output control processing will be described in detail in Chapter (5).
(3.2) Configuration of Image Data Processing Unit 43 Next, the configuration of the image data processing unit 43 will be described with reference to FIGS. 6, 8, and 9.

  The image data processing unit 43 sequentially writes the line configuration data input from the reading front end 41 to a buffer 45a as a FIFO memory provided in the local RAM 45, and for the line configuration data stored in the buffer 45a, It has a data processing function of performing image processing such as shading correction and gamma correction and writing the line configuration data after the image processing to the RAM 13 through the memory controller 63.

  Further, the image data processing unit 43 outputs a stop signal (stop_sig) for temporarily stopping the conveyance of the conveyance target based on the free capacity of the buffer 45a, and a restart signal (restart signal for resuming the conveyance of the conveyance target ( It has a stop / restart control function that outputs (restart_sig).

FIG. 8 is an explanatory diagram relating to the data processing function realized by the image data processing unit 43.
The image data processing unit 43 includes a data writing unit 43a, an image processing unit 43b, and a data transfer unit 43c as a configuration for realizing a data processing function, and line configuration data is input from the reading front end 41. Each time, the data writing unit 43a writes this line configuration data to the buffer 45a.

  Further, the image data processing unit 43 reads the line configuration data recorded at the reading position of the buffer 45a in the image processing unit 43b, performs image processing such as shading correction and gamma correction on the line configuration data, The line configuration data after the image processing is stored in the processing data storage unit 45b in the local RAM 45.

  In addition, the image data processing unit 43 sequentially writes pixel data (line configuration data) after image processing accumulated in the processing data storage unit 45b to the RAM 13 through the data transfer unit 43c. In this embodiment, the line data of each line is expressed by the combination of the line configuration data written in the RAM 13 as described above, and the image of the entire document is expressed by the combination of the line data.

  Then, for example, the image reading apparatus 1 outputs the original reading result to the external PC by sequentially outputting the line data written in the RAM 13 to the external PC through the external interface 23. The external PC generates image data representing the reading result of the entire document by combining these line data.

  In addition, when the image reading apparatus 1 is a multifunction peripheral having a copy function, for example, image data composed of a combination of line data written in the RAM 13 is an image representing the reading result of the entire document in the apparatus. As data, it is used for copy processing.

  Further, the functional blocks in the image data processing unit 43 shown in FIG. 6 are functional blocks related to the stop / resume control function. As illustrated in FIG. 6, the image data processing unit 43 includes a stop signal generation unit 43d that outputs a stop signal (stop_sig) and a restart signal generation unit 43e that outputs a restart signal (restart_sig).

  Specifically, the stop signal generator 43d executes the process shown in FIG. 9A to switch the state of the stop signal to be output. FIG. 9A is a flowchart showing processing executed by the stop signal generation unit 43d when the reading function is activated.

  When the process shown in FIG. 9A is started, the stop signal generation unit 43d sets the stop signal (stop_sig) to the value 0 (zero) (S310), and thereafter, acquisition of line configuration data up to the reading end line is performed. It is determined whether or not it is completed (S320). If the acquisition of the line configuration data up to the reading end line has been completed (Yes in S320), a reading end signal is output to notify each unit of the end of reading (S360), and then FIG. The process shown in (a) is terminated.

  On the other hand, if the acquisition of the line configuration data up to the reading end line has not been completed (No in S320), it is determined whether or not the free capacity rem_buf of the buffer 45a is equal to or smaller than a predetermined threshold B_lim ( S330). If the free capacity rem_buf of the buffer 45a is larger than the threshold value B_lim (No in S330), it is determined that there is sufficient free capacity for writing the line configuration data input from the reading front end 41, and the process proceeds to S310. Set the stop signal to the value 0.

  On the other hand, when the free capacity rem_buf of the buffer 45a is equal to or smaller than the threshold B_lim (Yes in S330), the stop signal generating unit 43d changes the stop signal from the value 0 to the value 1 (S340). Thereafter, the process proceeds to S320.

  In this way, when the stop signal is changed from the value 0 to the value 1, in this embodiment, the transport operation for the transport target is stopped and the output of the line configuration data from the reading front end 41 is stopped. . The stop signal whose state is switched in this way is input to the reading front end 41 and the drive stop command generating unit 49.

  In addition, the restart signal generator 43e executes the process shown in FIG. 9B to switch the state of the restart signal. FIG. 9B is a flowchart showing the processing executed by the restart signal generator 43e when the reading function is activated.

  When the restart signal generation unit 43e starts the process shown in FIG. 9B, the restart signal is first set to a value 0 (S410), and then whether or not the acquisition of the line configuration data up to the reading end line is completed. Is determined (S420). If the acquisition of the line configuration data up to the reading end line has been completed (Yes in S420), the process is paused.

  On the other hand, when the acquisition of the line configuration data up to the reading end line has not been completed (No in S420), it is determined whether or not the free capacity rem_buf of the buffer 45a is equal to or larger than a predetermined threshold B_th ( S430).

  If the free space rem_buf is equal to or greater than the threshold B_th (Yes in S430), the restart signal is changed from the value 0 to the value 1 assuming that the free space rem_buf in the buffer 45a is sufficient for restart (S440). ). Thereafter, the process proceeds to S420. Note that the threshold B_th is set to a value larger than the threshold B_lim (B_th> B_lim).

  In contrast, if the free capacity rem_buf of the buffer 45a is less than the threshold B_th (No in S430), the restart signal generation unit 43e proceeds to S410, assuming that the free capacity rem_buf of the buffer 45a is not sufficient for restarting. The restart signal is set to the value 0. Thereafter, the process proceeds to S420.

A restart signal whose state is switched in this way is input to the CPU 11. Further, the CPU 11 constantly monitors the restart signal. When the restart signal switches from the value 0 to 1, the CPU 11 inputs a reading restart command to the motor control unit 39, and performs the processing shown in FIG. The process is executed from S110. The CPU 11 also inputs a reading restart command to the reading control unit 21 and resets the motor drive stop command signal (mtstop) output from the drive stop command generation unit 49 to a value of zero.
(3.3) Configuration of Drive Stop Command Generation Unit 49 Next, the configuration of the drive stop command generation unit 49 will be described.

  The drive stop command generation unit 49 inputs a motor drive stop command signal (mtstop) to the motor control unit 39, and resets the motor drive stop command signal (mtstop) to a value of 0 when the reading function is activated. Based on the stop signal (stop_sig) input from the image data processing unit 43, the motor drive stop command signal is switched to the value 1.

  Specifically, when the stop signal (stop_sig) input from the image data processing unit 43 is 0, the drive stop command generating unit 49 does not switch the state of the motor drive stop command signal, and the image data processing unit It waits until the stop signal input from 43 switches to the value 1.

  When the stop signal (stop_sig) input from the image data processing unit 43 changes to the value 1, the motor drive input to the motor control unit 39 at the time when the edge detection signal is input from the encoder edge detection unit 31 thereafter. The stop command signal (mtstop) is switched to the value 1.

  In addition, after the motor drive stop command signal (mtstop) is switched to the value 1, the CPU 11 waits until the above-described reading restart command is input from the CPU 11, and when the reading restart command is input from the CPU 11, the motor drive stop command signal Reset (mtstop) to the value 0. The motor drive stop command signal (mtstop) is also reset to 0 when a reading end signal is input from the image data processing unit 43.

  In this way, when the stop signal (stop_sig) input from the image data processing unit 43 changes to the value 1, the drive stop command generation unit 49 switches the motor drive stop command signal (mtstop) from the value 0 to the value 1. Thereafter, the motor drive stop command signal (mtstop) is held at the value 1 until the reading restart command is input from the CPU 11 or the reading up to the final line is completed.

On the other hand, as described above, the motor control unit 39 to which the motor drive stop command signal is input shifts to S150 when the motor drive stop command signal (mtstop) is switched to the value 1, and the motor drive stop command signal Accordingly, the process of decelerating the rotation of the motor to be controlled and stopping the motor is performed. In this way, in the image reading apparatus 1 of the present embodiment, as shown in FIG. 3, whenever the free capacity of the buffer 45a decreases, the transport operation of the transport target is temporarily stopped, and the free capacity of the buffer 45a is recovered. Then, the transport operation for the transport target is resumed.
(4) LED lighting control process Subsequently, the LED lighting control process executed by the LED control signal generation unit 41c will be described with reference to FIG. FIG. 10 is a flowchart showing an LED lighting control process executed by the LED control signal generation unit 41c every time a line start trigger signal is input.

  When this process is started, the LED control signal generation unit 41c passes the remaining time T2 until the next input time of the line start signal from the input time of the line start trigger signal input this time, which is measured by the time measurement unit 50. It is calculated based on the time T1 and the input cycle T0 of the line start (trigger) signal (T2 = T0−T1).

  Further, a value (TE + γ) obtained by adding a predetermined margin amount γ to the lighting time TE, which is a time for lighting the LED, is calculated, and a value Δ = T2− (TE + γ) is obtained by subtracting the value (TE + γ) from the remaining time T2. It is determined whether or not it is equal to or less than zero (that is, whether or not Δ ≦ 0) (S710).

  If it is determined that Δ is less than or equal to zero (Yes in S710), the process proceeds to S750. If it is determined that Δ is greater than zero (No in S710), an edge detection signal is input or Δ is a value. It waits until it becomes zero or less (S710-S720). In addition, about the process of S710-S720, it performs with a period earlier than the time count by the time measurement part 50. FIG.

  When the edge detection signal is input (Yes in S720), the LED control signal generation unit 41c starts lighting the previous LED based on the value enc_pos updated by the position detection unit 33 by the input of the edge detection signal. It is determined from the previous lighting start position pre_pos that is the position where the conveyance target exists at the time when the conveyance target has moved by 1/3 line distance (α / 3) in the image reading direction.

  The previous lighting start position pre_pos is stored and held by the process of S760 described later. However, the previous lighting start position pre_pos is the time when the initial line start trigger signal is input from the line start trigger signal generation unit 41a to the LED control signal generation unit 41c (in other words, the conveyance target is the reading start position (start_enc)). Is set to an initial value (position that is 1/3 line back from the position where the first lighting should start).

  In this embodiment, a distance α corresponding to one line in the sub-scanning direction (hereinafter referred to as “one line distance”) is set in the register RG2 in advance, and in S730, the one line distance set in the register RG2. Based on α, it is determined whether or not the conveyance target has moved from the previous lighting start position pre_pos in the image reading direction by 1/3 line distance (α / 3), which is one third of the line distance α.

  Specifically, a displacement amount L = enc_pos−pre_pos from the previous lighting start position pre_pos to the current position enc_pos to be transported is calculated, and whether or not the displacement amount L is equal to or greater than 1/3 line distance (α / 3). (That is, whether L ≧ (α / 3)) is determined.

  If it is determined that the object to be transported has not moved 1/3 line distance (α / 3) in the image reading direction from the previous lighting start position pre_pos (No in S730), the LED control signal generation unit 41c The process shifts to S710 and waits until an edge detection signal is input or the value Δ is equal to or less than zero (S710 to S720), as in the above-described process.

  On the other hand, when it is determined that the conveyance target has moved by 1/3 line distance (α / 3) in the image reading direction from the previous lighting start position pre_pos (Yes in S730), the process proceeds to S740, and the current time is prohibited from lighting. It is determined whether it is a period.

  In this embodiment, a predetermined time is determined as the lighting prohibition period from the time when the line start signal is input to the CIS line sensor 20 (see FIG. 12B), and the LED control signal generator 41c is Whether or not the current time is the lighting prohibited period is determined based on the elapsed time T1 from the input time of the line start trigger signal.

  And when the present time is a lighting prohibition period, it waits until a lighting prohibition period is complete | finished, and it transfers to S760 after that. On the other hand, if the current time is not the lighting prohibited period, the process proceeds to S760 without waiting.

  In S760, the LED control signal generation unit 41c stores and holds the value enc_pos currently input from the position detection unit 33 as the previous lighting start position pre_pos, and then sets the LED of the lighting target color set in advance. The light is turned on for a predetermined time TE (S770). For example, when the lighting target color is set to red, the LED 20R is lit for a predetermined time TE among the LEDs 20R, 20G, and 20B. When the predetermined time TE elapses, the LED is turned off and the data valid flag is set to ON (S780).

  The lighting target color is changed to red, which is an initial value, by the operation of the LED control signal generation unit 41c when the initial line start trigger signal is input from the line start trigger signal generation unit 41a to the LED control signal generation unit 41c. Is set. Similarly, the data valid flag is set to OFF as an initial value when the initial line start trigger signal is input.

  Returning to the description, the LED control signal generation unit 41c sets the data valid flag to ON (S780), and then sets the lighting target color to the next color (S790). Specifically, the LED control signal generation unit 41c sets green as the next color when the lighting target color is set to red, and sets the next color when the lighting target color is set to green. When blue is set and the lighting target color is set to blue, red is set as the next color.

  In this way, when the lighting target color is switched, the LED control signal generation unit 41c ends the LED lighting control process. Then, when a new line start trigger signal is input, the LED lighting control process is started again from S710.

  On the other hand, in S710, it is determined that Δ is less than or equal to zero, and when the process proceeds to S750, the LED control signal generation unit 41c determines that the object to be transported is in a time zone before the next line start (trigger) signal is input. Considering the possibility of moving by 1/3 line distance (α / 3) in the image reading direction from the previous lighting start position pre_pos, it is determined whether or not the LED should be turned on ahead and executed.

Specifically, it is determined as follows whether or not the LED should be turned on in advance.
That is, when the transfer target is moving at the target transfer speed Vr, the distance D = Vr · T2 is calculated for the remaining time T2, and the 1/3 line distance (α / 3) from the previous lighting start position pre_pos. The advanced position is calculated as the ideal lighting start position next_pos (next_pos = pre_pos + α / 3).

  Then, based on the value enc_pos representing the current position of the conveyance target input from the position detection unit 33, whether or not the difference between the ideal lighting start position next_pos and the current position enc_pos of the conveyance target is less than the distance D (that is, D > (Next_pos-enc_pos).

  In the case of D ≦ (next_pos−enc_pos), even when the transport target is moving at the target transport speed Vr that is the maximum speed, it takes more than the remaining time T2 to reach the ideal lighting start position next_pos. Therefore, during the period from the present time until the next line start (trigger) signal is input, the conveyance target does not reach the ideal lighting start position next_pos, and the lighting of the LED should not be executed ahead of schedule. .

  On the other hand, in the case of D> (next_pos-enc_pos), the conveyance target is 1/0 in the image reading direction from the previous lighting start position pre_pos in the time zone before the input time of the next line start (trigger) signal. Since there is a possibility of moving by a distance of 3 lines (α / 3), the LED should be turned on in advance.

  Therefore, in S750, if D ≦ (next_pos-enc_pos), it is determined that the LED should not be turned forward and executed. If D> (next_pos-enc_pos), the LED is turned forward and executed. Judge that it should be.

  If it is determined that the LED should be turned on ahead of time (Yes in S750), the LED control signal generation unit 41c proceeds to S760, and executes the processes of S760 to S790 in the above-described procedure. As a result, the LED of the lighting target color is turned on for a certain period of time TE, and after the data valid flag is turned on, the LED lighting control process is terminated.

  On the other hand, if it is determined that the lighting of the LED should not be performed ahead of time (No in S750), the LED lighting control processing is not performed without turning on any LED and without turning on the data valid flag. finish.

  The above is the content of the LED lighting control process. However, the above-described margin amount γ can be set to a value equal to or greater than zero at the design stage in consideration of the time required from when it is determined Yes in S710 until the LED is actually turned on. Specifically, it is determined that the lighting of the LED corresponding to the time TE is always completed before the next line start signal is input to the CIS line sensor 20.

  In this way, in this embodiment, when it is determined Yes in S750, the LED of the LED is displayed on the CIS line sensor 20 at the time when the time TE goes back from the time when the next line start signal is input or when it goes back further. Start lighting. However, the margin amount γ is preferably set to a minimum value as long as the above condition is satisfied.

  Here, LED lighting modes realized by the above-described LED lighting control processing will be described with reference to FIGS. 11 and 12. FIGS. 11 and 12 are time charts showing lighting modes of LEDs.

In the present embodiment, there is the following relationship among the target transport speed Vr during constant speed transport, the line start signal input period T0, and the 1/3 line distance (α / 3).
α / 3 = Vr · T0
That is, when the transport target is transported at the target transport speed Vr at time T0, the transport target moves by 1/3 line distance (α / 3). Therefore, at the time of constant speed conveyance, the input cycle of the line start signal and the lighting cycle of the LED coincide with each other, and as shown in the upper part of FIG. 11, every time the line start signal is input to the CIS line sensor 20, the LED Is turned on, and the LED lighting control is apparently performed in the same manner as in the conventional apparatus.

  On the other hand, at the time of acceleration / deceleration, a line start signal is input to the CIS line sensor 20 at a constant period T0, whereas the LED is turned on every time the conveyance target advances by a 1/3 line distance in accordance with the movement of the conveyance target. Therefore, as shown in the lower part of FIG. 11, the LEDs are lit independently in response to the input of the line start signal.

  However, regardless of the input of the line start signal, if the LED is turned on every time the object to be transported advances 1/3 line distance, the line start signal is input during the period when the LED is turned on, and the charge of the light receiving element is reduced. It may be reset.

  For this reason, in this embodiment, when the lighting of the LED is started on the condition that the object to be transported has moved to the ideal lighting start position advanced by a distance of 1/3 line from the previous lighting start position pre_pos, The possibility that the line start signal is input to the CIS line sensor 20 before the end of the minute is determined based on the possibility of the transport target reaching the ideal lighting start position within the remaining time T2 (S750). If there is a property (Yes in S750), as shown in FIG. 12A, the LED is turned forward and the LED is turned on (S770).

  In addition, in this embodiment, since it is necessary to transfer the signal charge to the shift register and reset the light receiving element for a while after the line start signal is input to the CIS line sensor 20, in this embodiment, the line start signal The time until a predetermined time elapses from the input start time is set as the lighting prohibition period, and when the object to be transported reaches the ideal lighting start position at this time, it waits until the lighting prohibition period ends. Then, after the end of the lighting prohibition period, the LED is turned on as shown in FIG.

In this way, in this embodiment, no problem occurs even if the input of the line start signal and the lighting timing of the LED are asynchronous.
(5) Output Control Process Next, the output control process executed by the output control unit 41e will be described with reference to FIG. FIG. 13 is a flowchart showing an output control process executed by the output control unit 41e each time a line start trigger signal is input.

  When the line start trigger signal is input and the output control process is started, the output control unit 41e sets the data valid flag by the LED lighting control process executed by the LED control signal generation unit 41c by the input of the line start trigger signal. Before updating, the value of the data valid flag updated or maintained in the previous LED lighting control process is read, and it is determined whether or not the data valid flag is set to ON in the previous LED lighting control process. (S810).

  If it is determined that the data valid flag is set on (Yes in S810), the process proceeds to S820, the data valid flag is set off, and the CIS line sensor is set in response to the input of the current line start trigger signal. The pixel data group representing the previous reading result transferred from 20 is input to the image data processing unit 43 as line configuration data (S830). Thereafter, the output control process ends.

  On the other hand, if it is determined in the previous LED lighting control process that the data valid flag is not set to ON and maintained off (No in S810), the output control unit 41e proceeds to S840, and formally data valid In addition to setting the flag to OFF, all the pixel data groups transferred from the CIS line sensor 20 in response to the input of the current line start trigger signal are discarded and are not transferred to the image data processing unit 43. (S850). Thereafter, the output control process ends.

In this way, the output control unit 41e prevents the LED control signal generation unit 41c from transferring the pixel data group representing the read result of the cycle in which the LED is not lit downstream, and generates the LED control signal. The unit 41c transfers the pixel data group representing the read result of the cycle in which the LED is lit downstream.
(6) Effects, etc. In order to generate image data of the entire original so as to avoid unevenness when generating line data of each color to generate image data of the entire original, each line configuration data is aligned with the light receiving time. Must be generated so that the brightness of the line configuration data does not vary, and the image data of the entire document must be constructed using line configuration data read at equal intervals in the sub-scanning direction. .

  For this reason, conventionally, image data of the entire document is constructed using only pixel data generated during constant-speed conveyance in which a conveyance target is conveyed by a certain distance in a certain time, but only during constant-speed conveyance. When the pixel data is used, the reading efficiency is poor.

  For example, if a large buffer cannot be secured due to the cost and the free space in the buffer 45a is insufficient due to processing delay in the image processing unit 43b as in this embodiment, the transport operation is temporarily stopped. However, if the pixel data at the time of acceleration / deceleration cannot be used, it is necessary to return the conveyance target to a point before the interruption point so as to be in a constant speed conveyance state at the interruption point. . Therefore, the conveyance target moves twice in the vicinity of the interruption point, which is inefficient.

  Further, the ADF apparatus has a problem that troubles such as a jam are likely to occur when the document is conveyed in the reverse direction. Furthermore, it is difficult from the cost and technical viewpoints to adopt a structure that does not cause troubles such as jamming due to reverse running of the document. Therefore, the ADF apparatus has a problem that it is difficult to adopt a method of returning a document in the first place.

  On the other hand, in the image reading apparatus 1 according to the present embodiment, while the line start signal is periodically input to the CIS line sensor 20, the lighting control of the LED is adjusted at approximately equal intervals according to the movement of the conveyance target. By executing, the CIS line sensor 20 is caused to execute a substantial reading operation in accordance with the movement of the conveyance target while keeping the light receiving time constant.

  According to the present embodiment that realizes reading in this way, the input timing of the line start signal input to the reading unit is not changed according to the movement of the conveyance target as in the prior art. There is no problem of dark current, and brightness does not vary due to a change in the speed of the conveyance target.

  Therefore, according to the present embodiment, the original can be appropriately read even at the time of acceleration / deceleration, the image data of the entire original can be generated uniformly using the reading result at the time of acceleration / deceleration, and the buffer 45a is free. Even when the transfer operation is temporarily interrupted due to a shortage of capacity, it is not necessary to return the transfer target before the interruption point.

  Therefore, according to the image reading apparatus 1 of the present embodiment, reading efficiency can be improved, and a document can be read at high speed. In addition, since the ADF device does not require an increase in the capacity of the buffer 45a, there is an advantage that a product can be manufactured at low cost.

  Further, according to the image reading apparatus 1 of the present embodiment, the reading start position start_enc is set at a point before the conveyance target is conveyed at a constant speed, or before the reading operation for all lines is completed, The apparatus can be configured to perform a reading operation up to the final line in a decelerated state.

  In addition, what is necessary is just to change the process performed in S120 as follows, when decelerating a conveyance target before the reading operation for all the lines is completed. That is, the process executed in S120 may be changed to a process of starting deceleration when the conveyance target reaches the deceleration start position designated by the CPU 11 while the conveyance target is being transported at a constant speed.

In this way, the moving range in the sub-scanning direction of the CIS line sensor 20 necessary for reading the entire document is narrowed, so that the image reading apparatus 1 can be downsized in the sub-scanning direction. (7) Others While the embodiments of the present invention have been described above, the reading unit of the present invention corresponds to the CIS line sensor 20, and the transport means is the transport mechanism of the carriage 106, the ADF device 150, and the drive control unit 17. Equivalent to. The signal input means corresponds to the line start signal generator 41b, and the capture means corresponds to the transfer clock signal generator 41d and the output controller 41e. In addition, the measurement unit corresponds to the encoders EN1 and EN2 and the encoder processing unit 15, and the lighting control unit is realized by the LED control signal generation unit 41c.

  In particular, the determination means is realized by the processes of S710 and S750, and the forward lighting control means does not execute the processes of S720 to S740 when the determination of Yes is made in S710, the conveyance target is 1/3 line distance. This is realized by the operation of the LED control signal generation unit 41c that turns on the LED even if the condition is not satisfied while the LED is not executed on the condition that the LED has advanced.

  In addition, if the current time is a lighting prohibited period, the delayed lighting control means does not turn on the LED until the lighting prohibited period elapses, and LED control that turns on the LED after the lighting prohibited period elapses. This is realized by the operation of the signal generation unit 41c.

Further, the data output means is realized by an operation in which the output control unit 41e switches whether to output line configuration data according to ON / OFF of the data valid flag.
Further, the present invention is not limited to the above-described embodiments, and can take various forms. For example, the determination as to whether or not to advance the lighting of the LED in S750 may be performed using the current moving speed V of the conveyance target.

  If the remaining time until the next line start signal input time is time T2 and the moving speed of the transfer target is V at the time of determination, the transfer target is moved from the current position enc_pos until the next line start signal is input. The distance V · T2 is expected to advance.

  Therefore, if the distance from the current position to the ideal lighting start position next_pos (next_pos-enc_pos) satisfies the conditional expression (next_pos-enc_pos) ≧ V · T2, it is determined that the LED should not be turned on ahead of time and executed. However, if (next_pos-enc_pos) <V · T2, the image reading apparatus 1 may be configured to determine that the LED should be turned on ahead of time and executed.

Thus, even when the image reading apparatus 1 is configured, the same effects as those of the above-described embodiment can be obtained.
In addition, in the above-described embodiment, the image reading apparatus that realizes the reading operation by receiving the light reflected from the light source and returning to the original document has been described. The present invention can also be applied to an image reading apparatus that receives (transmitted light) and realizes a reading operation.

2 is a block diagram illustrating an electrical configuration of the image reading apparatus 1. FIG. 2 is a cross-sectional view showing a mechanical configuration of the image reading apparatus 1. FIG. It is explanatory drawing showing the conveyance aspect of the CIS line sensor. 3 is a block diagram illustrating configurations of an encoder processing unit 15 and a drive control unit 17. FIG. 4 is a flowchart illustrating processing executed by a motor control unit 39. 3 is a block diagram illustrating a configuration of a reading control unit 21. FIG. 3 is an explanatory diagram showing a configuration of a time measuring unit 50. FIG. 3 is a block diagram illustrating a configuration of an image data processing unit 43. FIG. It is a flowchart showing the process which the stop signal production | generation part 43d and the restart signal production | generation part 43e perform. It is a flowchart showing the LED lighting control process which the LED control signal generation part 41c performs. It is the time chart which showed the lighting mode of LED. It is the time chart which showed the lighting mode of LED. It is a flowchart showing the output control process which the output control part 41e performs.

DESCRIPTION OF SYMBOLS 1 ... Image reading device, 11 ... CPU, 12 ... ROM, 13 ... RAM, 15 ... Encoder processing part, 17 ... Drive control part, 20 ... CIS line sensor, 20R, 20G, 20B ... LED, 21 ... Reading control part, DESCRIPTION OF SYMBOLS 23 ... External interface, 31 ... Encoder edge detection part, 33 ... Position detection part, 35 ... Speed detection part, 37 ... Drive circuit, 39 ... Motor control part, 41 ... Reading front end, 41a ... Line start trigger signal generation part, 41b ... Line start signal generation unit, 41c ... LED control signal generation unit, 41d ... Transfer clock signal generation unit, 41e ... Output control unit, 43 ... Image data processing unit, 43a ... Data writing unit, 43b ... Image processing unit, 43c ... Data transfer unit, 43d ... Stop signal generation unit, 43e ... Resumption signal generation unit, 45 ... Local RAM, 45a ... Buffer, 45 ... Processing data storage unit 49 ... Drive stop command generating unit 50 ... Time measuring unit 63 ... Memory controller 101 ... Main body of apparatus 102 ... Standing reading window 102A, 103A ... Platen 103 ... Automatic reading window 104 ... Document cover 106 ... Carriage 107, 108 Pulley 109 109 Belt 111 Guide shaft 150 ADF device 153 Separation roller 154 Separation pad 155 Suction roller 159 Feed roller 160 Pinch roller, 161 ... Document pressing, 162 ... Discharge roller, 164 ... Document sensor actuator, 165,166 ... Tray, 201 ... Light receiving element group, 203 ... Shift register, EN1, EN2 ... Encoder, MT1, MT2 ... Motor, RG1 , RG2 ... Register

Claims (7)

Irradiating means for irradiating light on a document to be read;
A light receiving unit for each pixel that receives reflected light or transmitted light of the light irradiated to the original by the irradiation unit is provided along the main scanning direction, and corresponds to the amount of light received accumulated in each light receiving unit. Provided with a pixel holding unit for storing and holding signal charge information, each time a start signal is input, signal charge information representing a reading result of the original accumulated in each light receiving unit in a period until the input, A reading unit that holds the pixel data in the pixel holding unit and resets the light receiving units;
Signal input means for periodically inputting the start signal to the reading unit;
Conveying means for conveying one of the reading unit and the document in the sub-scanning direction as a conveyance target;
Whenever the start signal is input to the reading unit by the signal input unit, the pixel data group held in the pixel holding unit by the input of the start signal is used as image data for one unit from the pixel holding unit. Capture means for capturing; and
Including a signal generator that generates an edge signal each time the conveyance target is displaced by a predetermined amount in the sub-scanning direction, and updating a measurement value for the conveyance amount of the conveyance target each time the edge signal is generated, Measuring means for measuring the transport amount of the transport object in the sub-scanning direction ;
A means for causing the irradiating means to perform an irradiating operation in accordance with the generation of the edge signal, wherein each time the edge signal is generated , the transport target is preliminarily determined based on the measured value updated by the generation of the edge signal; It is determined whether or not it has been displaced in the sub-scanning direction by a specified amount corresponding to a predetermined reading interval in the sub-scanning direction, and if it is determined that the specified amount has been displaced, the timing immediately after the generation of the edge signal is determined From the lighting control means for causing the irradiation means to perform an irradiation operation for a predetermined time that is shorter than the output period of the start signal by the signal input means,
An image reading apparatus comprising: Irradiating means for irradiating light on a document to be read;
A light receiving unit for each pixel that receives reflected light or transmitted light of the light irradiated to the original by the irradiation unit is provided along the main scanning direction, and corresponds to the amount of light received accumulated in each light receiving unit. Provided with a pixel holding unit for storing and holding signal charge information, each time a start signal is input, signal charge information representing a reading result of the original accumulated in each light receiving unit in a period until the input, A reading unit that holds the pixel data in the pixel holding unit and resets the light receiving units;
Signal input means for periodically inputting the start signal to the reading unit;
Conveying means for conveying one of the reading unit and the document in the sub-scanning direction as a conveyance target;
Whenever the start signal is input to the reading unit by the signal input unit, the pixel data group held in the pixel holding unit by the input of the start signal is used as image data for one unit from the pixel holding unit. Capture means for capturing; and
Measuring means for measuring the transport amount of the transport object;
Based on the measurement result of the measuring means, each time the conveyance object is displaced in the sub-scanning direction by a predetermined amount corresponding to a predetermined reading interval in the sub-scanning direction, a start signal from the signal input means is sent to the irradiation means. A lighting control means for executing the irradiation operation for a predetermined time that is shorter than the output cycle,
Whether or not the first timing, which is the timing at which the lighting control means will cause the irradiation means to start the irradiation operation next time, is prior to the second timing, which is the timing at which the start signal is input to the reading unit next time Determining means for executing the determination at a time before a predetermined margin amount before the specified time before the second timing;
When the determination means determines that the first timing is before the second timing, the execution of the irradiation operation scheduled to be executed at the first timing is prohibited and the execution is prohibited. Instead of irradiating operation, forward lighting control for causing the irradiating means to start the irradiating operation for the specified time at any time from the time when the determination is made by the determining means to the specified time before the second timing. Means,
An image reading apparatus comprising: Irradiating means for irradiating light on a document to be read;
A light receiving unit for each pixel that receives reflected light or transmitted light of the light irradiated to the original by the irradiation unit is provided along the main scanning direction, and corresponds to the amount of light received accumulated in each light receiving unit. Provided with a pixel holding unit for storing and holding signal charge information, each time a start signal is input, signal charge information representing a reading result of the original accumulated in each light receiving unit in a period until the input, A reading unit that holds the pixel data in the pixel holding unit and resets the light receiving units;
Signal input means for periodically inputting the start signal to the reading unit;
Conveying means for conveying one of the reading unit and the document in the sub-scanning direction as a conveyance target;
Whenever the start signal is input to the reading unit by the signal input unit, the pixel data group held in the pixel holding unit by the input of the start signal is used as image data for one unit from the pixel holding unit. Capture means for capturing; and
Measuring means for measuring the transport amount of the transport object;
Based on the measurement result of the measuring means, each time the conveyance object is displaced in the sub-scanning direction by a predetermined amount corresponding to a predetermined reading interval in the sub-scanning direction, a start signal from the signal input means is sent to the irradiation means. A lighting control means for executing the irradiation operation for a predetermined time that is shorter than the output cycle,
With
The predetermined time from the input time of the start signal is set as a prohibition period for prohibiting the irradiation operation by the irradiation means,
In further,
In the prohibition period, the lighting control unit prohibits the operation of causing the irradiation unit to execute the irradiation operation, and instead of the prohibited irradiation operation, the irradiation unit is instructed to pass the prohibition period. images reader you further comprising a delay lighting control means for starting the irradiation operation of the specified time. The predetermined time from the input time of the start signal is set as a prohibition period for prohibiting the irradiation operation by the irradiation means,
The image reading apparatus further includes:
In the prohibition period, the lighting control unit prohibits the operation of causing the irradiation unit to execute the irradiation operation, and instead of the prohibited irradiation operation, the irradiation unit is instructed to pass the prohibition period. The image reading apparatus according to claim 2, further comprising: a delayed lighting control unit that starts an irradiation operation for a specified time. The lighting control means prohibits execution of the irradiation operation by the forward lighting control means, and instead of the prohibited irradiation operation, the specified time of the second timing from the time when the determination is made by the determination means. When the irradiation unit starts the irradiation operation for the specified time at any time before, the transfer target is moved from the position of the transfer target at the time when the irradiation unit starts the irradiation operation. the prescribed amount, each time displaced in the sub-scanning direction, the image reading apparatus according to claim 2 or claim 4, wherein the being to configured to perform the irradiating operation of the predetermined time to said irradiation means. The lighting control means, when the delayed lighting control means causes the irradiation means to start the irradiation operation for the specified time when the prohibition period has elapsed, when the irradiation means starts the irradiation operation The irradiation unit is configured to execute an irradiation operation for the specified time every time the transfer target is displaced in the sub-scanning direction by the specified amount from the position of the transfer target in the above. Alternatively, the image reading apparatus according to claim 4 . Of the image data captured by the capturing unit from the reading unit, image data including information on signal charges accumulated in the light receiving unit during a period when the irradiation operation by the irradiation unit is executed is selectively selected. The image reading apparatus according to claim 1, further comprising a data output unit configured to output to the outside.