JP2012165227A - Image reader and image reading control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reading image quality even when a motor speed is not stable during an acceleration period or deceleration period.SOLUTION: The image reader executes four-shift control that outputs a shift signal that is electrical charge storage start timing corresponding to each color of RGB and a dummy shift signal after an output of the shift signal corresponding to the each color of RGB for each line.

Description

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

An image reading apparatus such as a copying apparatus or a scanner apparatus that reads an original scans the original with an image sensor and reads an image. The image sensor is attached to the carriage, and the original can be scanned by moving the carriage by a driving mechanism having a motor as a driving source.

In the document reading operation, while the carriage moves, the light from the light source provided on the carriage is irradiated onto the document surface, and the image sensor accumulates the light reflected from the document surface for a predetermined time, This is converted into an electrical signal and output to the image processing means as an image signal. In this reading operation, the image signal stored for a predetermined time is transferred as an image signal at a predetermined timing, whereby the image is read while scanning line by line.

The image sensor is, for example, a transfer timing signal for each color of RGB for each line given from the image processing means (for example, a shift signal, a shift pulse, a trigger signal, etc.).
The image signal of each color of RGB of each line is transferred according to the above. The image processing means generates a transfer timing signal based on an encoder signal that outputs a pulse signal corresponding to the rotation amount of the motor, measures time using a timer, and transfers the transfer timing at a predetermined time interval from the encoder signal. Generate a signal.

JP 2007-028170 A

By the way, in the movement of the carriage, the acceleration period (acceleration region) is from the start to the end of the movement.
A constant speed period (constant speed (constant speed) region) and a deceleration period (deceleration region) are passed. In the constant speed period,
Since the motor speed is stable, the transfer timing signal is stably output at approximately equal intervals. For this reason, the electrical signals of the respective colors of the respective lines are accumulated in the image sensor for an ideal time.

However, in the deceleration period, the motor speed is reduced, so that the encoder signal interval becomes longer than the interval in the constant speed period. For this reason, the accumulation time of the electrical signals of the respective colors in each line also becomes longer, which affects the image quality.

This will be specifically described with reference to FIG. FIG. 6 is a timing chart of conventional image reading control (deceleration period).

The position trigger is a transfer timing signal that is generated based on an encoder signal that is output according to the rotation of the motor. The repeat trigger is a transfer timing signal generated at a predetermined time interval by a repeat timer on the basis of the position trigger. The free run trigger is a transfer timing signal generated at a predetermined time interval by a free run timer with reference to a position where it is determined that the motor has stopped.

In the example of this figure, the LEDs are repeatedly turned on in the order of RGB. Also, the B charge is transferred by the position trigger, the R charge is transferred by the repeat trigger immediately after the position trigger, and the G charge is transferred by the next repeat trigger. That is, three shift signals corresponding to each RGB color are output for each line. Hereinafter, this control method is also referred to as “3-shift control”.

Here, since the rotational speed of the motor is constant during the constant speed period, the position trigger is generated at an ideal interval I (T10, T20, T30). The repeat trigger is generated at an interval i from the position trigger (T11, T12, T21, T22, T31, T3
2). Further, the interval between the repeat trigger (T12, T22) for transferring the charge of G and the position trigger (T20, T30) immediately after them is a constant interval.
Therefore, charges corresponding to RGB colors of each line are accumulated for an ideal time.

On the other hand, during the deceleration period, the rotation of the motor is gradually decelerated.
The position trigger interval is longer than the ideal interval I in the constant speed period (I
', I'',I'''). That is, during the deceleration period, the output of the position trigger is gradually delayed (T40, T50, T60), so that the repeat trigger (G
T32, T42, T52) and the position trigger (T40, T50, T60) just after that
) Is longer than a certain interval in the constant speed period. Therefore, B
Even after the time for accumulating the color charge becomes longer and the B-color LED is turned off, unnecessary charge is accumulated (“noise” in the figure). As a result, the B-color charge (T40, transferred to the image processing means)
The noise information (“dark part noise”) in the image information and valid data that starts to be transferred at T50 and T60
Etc.), which affects the read image quality.

After the motor drive is stopped, a free run trigger is output (T70, T71).
When the interval I ″ ″ between the repeat trigger (T62) for transferring the charge of G and the free-run trigger (T70) immediately after it is longer than the predetermined interval in the constant speed period, B The color charge includes a noise component.

Similarly, since the rotation of the motor is gradually accelerated during the acceleration period, the position trigger interval becomes longer than the ideal interval I during the constant speed period as the distance from the constant speed period increases. For this reason, a noise component is included in the B color charge, which affects the image quality.

Therefore, an object of the present invention is to improve reading image quality when the motor speed is not stable during an acceleration period, a deceleration period, or the like.

One embodiment of the present invention for solving the above-described problem is an image reading apparatus, in which an image sensor that transfers charges accumulated in a photoelectric conversion element to a shift register by a shift signal, and an output timing of the shift signal Control means for controlling, a motor for moving a carriage for carrying the image sensor, and an encoder for detecting and outputting the rotation amount of the motor, the control means for each color of RGB for each line. 3 shift control for outputting a shift signal that is a charge accumulation start timing, and for each line, in addition to a shift signal that is a charge accumulation start timing corresponding to each RGB color, a predetermined signal is output after the shift signal corresponding to each RGB color is output 4 shift control that outputs a dummy shift signal is selectively executed, and the encoder Determining the motor speed based on the force, selecting the 4-shift control if the motor speed is below a predetermined speed, and selecting the 3-shift control if the motor speed exceeds a predetermined speed; It is characterized by.

Here, the image reading apparatus includes processing means for processing an image signal from the image sensor, and the processing means uses a shift signal corresponding to a predetermined reference color when the 4-shift control is selected. The image signal output from the image sensor may be processed as invalid data.

In addition, the image reading apparatus includes light sources corresponding to RGB colors, and the control unit includes light sources of corresponding colors in accordance with a shift signal that is a charge accumulation start timing of the RGB colors in the 4-shift control. The light source may be turned on, and any light source may not be turned on with the predetermined dummy shift signal.

In the four-shift control, when the output result of the encoder is in a predetermined state, the control means outputs a shift signal that is a charge accumulation start timing corresponding to the predetermined reference color, and the predetermined reference This is the charge accumulation start timing corresponding to each color other than the predetermined reference color when a predetermined time has elapsed for each color other than the predetermined reference color with reference to the charge accumulation start timing corresponding to the color. After the shift signal is output and the shift signal, which is the charge accumulation start timing corresponding to each color other than the predetermined reference color, is output, the charge accumulation start timing corresponding to the predetermined reference color is determined as a reference. The predetermined dummy shift signal may be output when time elapses.

The period in which the 4-shift control is executed may include at least a part of an acceleration period and a deceleration period of the motor.

Another aspect of the present invention for solving the above problem is an image reading control method in an image reading apparatus, wherein the image reading apparatus transfers charges accumulated in a photoelectric conversion element to a shift register by a shift signal. 3 shift control that outputs a shift signal that is a charge accumulation start timing of each color of RGB for each line, and an image sensor that moves the carriage that carries the image sensor. In addition, in addition to the shift signal that is the charge accumulation start timing corresponding to each RGB color, one of the four shift controls that outputs a predetermined dummy shift signal after outputting the shift signal corresponding to each RGB color is selectively executed. The speed of the motor is judged, and when the motor speed is equal to or lower than a predetermined speed, the 4-shift control is selected. , It selects the third shift control when the motor speed exceeds a predetermined speed, characterized in that.

1 is a schematic configuration diagram of an image reading apparatus according to an example of an embodiment of the present invention. It is a timing chart of image reading control (acceleration period) concerning an example of one embodiment of the present invention. 6 is a timing chart of image reading control (deceleration period) according to an example of an embodiment of the present invention. FIG. 6 is a flowchart illustrating processing (reading control processing) executed by the image reading apparatus according to an example of an embodiment of the present invention. It is a flowchart explaining the process (periodic interruption process) which the image reading apparatus which concerns on an example of one Embodiment of this invention performs. It is a timing chart of conventional image reading control (deceleration period).

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of an image reading apparatus according to an example of an embodiment of the present invention.

The image reading apparatus 10 is a so-called flat bed type image reading apparatus having a document table (not shown) on the upper surface of a housing. The image reading device 10 reads an image of a document placed on a document table of a transparent plate by the image sensor 220.

The image reading apparatus 10 includes a carriage 2 on which a light source 210 and an image sensor 220 are mounted.
00, a drive mechanism 300 that controls the movement of the carriage 200, and a control unit 100 that controls the entire image reading apparatus 10 and performs various processes for reading an image.

The carriage 200 carries the image sensor 220 together with the light source 210 in the sub-scanning direction. The carriage 200 is slidably attached to a guide shaft or the like parallel to the platen surface of the document table, and a motor (for example, a DC motor) 31 of the drive mechanism 300.
It is pulled by a belt that rotates by zero. The amount of movement of the carriage 200 depends on the driving mechanism 3.
Control is performed based on an output signal of an encoder 320 that outputs an encoder signal in accordance with a predetermined rotation amount of the 00 motor 310.

The light source 210 includes, for example, a red LED, a green LED, and a blue LED, and generates light of three colors of RGB in a predetermined order. In the present embodiment, the light source 210 emits light in the order of a red LED, a green LED, and a blue LED when performing image reading for one line. And
In order to read an image for a plurality of lines, the same light emitting operation is repeated. The light emission time of each color LED is predetermined for each color, and is extinguished when the predetermined time elapses after lighting.

In the following, among the three colors of RGB, the first light emission color in the light emission operation for one line is “
It is called “reference color”. Note that the light emission order is not limited to the RGB order.

The image sensor 220 receives the light reflected by the document, accumulates electric charges corresponding to the amount of received light, and sends the charges to the control unit 100 as image reading data (electrical signals).

The image sensor 220 includes a plurality of sensor chips arranged in the main scanning direction. Each sensor chip has the same configuration as, for example, a normal CCD (Charge Coupled Device) image sensor. That is, each sensor chip includes a photoelectric conversion element (photodiode PD), a shift gate, and a shift register. Then, the charge accumulated in the photoelectric conversion element is transferred to the shift register by opening the shift gate, and output while sequentially moving the charge by the shift register.

The opening of the shift gate (charge transfer) is performed in response to application of a trigger signal (a signal from a read control unit 120 described later) that is a transfer timing signal. Here, since the photoelectric conversion element always accumulates charges according to the amount of received light, the transfer timing of the charges to the shift register is the start timing of accumulating charges for the light of the next emission color. Become. Then, the charge transferred to the shift register is converted into an electric signal (analog data) by the output unit at the end of the shift register, and is sent to the A / D conversion unit 110.

The control unit 100 includes an A / D conversion unit 110 that converts analog data output from the image sensor 220 into digital data, and a data processing unit that performs various corrections on the digital data output from the A / D conversion unit 110. 130, a storage unit 140 that stores digital data for the data processing unit 130 to perform various corrections, an output unit 150 for sending data from the data processing unit 130 to a host such as a personal computer, and the like in the control unit 100 And a reading control unit 120 that controls the light source 210 and the image sensor 220 in the carriage 200 and the driving mechanism 300.

  Note that the A / D converter 110 may be mounted on a substrate in the carriage 200.

The reading control unit 120 controls the rotation of the motor 310 of the driving mechanism 300, thereby
The movement of the carriage 200 is controlled.

Further, the reading control unit 120 controls image reading of the image sensor 220, reading of white reference data, and reading of black reference data. Specifically, the image sensor 220.
Is supplied with a trigger signal to control the transfer timing of charge accumulated in the photoelectric conversion element to the shift register (next charge accumulation start timing). In order to perform this control, the reading control unit 120 includes a timer unit 121. The reading control unit 120 controls transfer of data read by the image sensor 220 to the A / D conversion unit 110.

In addition, the reading control unit 120 controls turning on and off of the light source 210 in accordance with the reading operation of the image sensor 220.

The data processing unit 130 performs various corrections such as shading correction on the digital data output from the A / D conversion unit 110 and outputs the digital data to the output unit 150. For example, when performing shading correction, the data processing unit 130 stores the image data, white reference data, and black reference data output from the A / D conversion unit 110 in the storage unit 140 described later, and corresponding pixels. Each time, shading correction is performed according to a predetermined correction formula. After correction, data processing unit 1
30 outputs the corrected image data to the output unit 150.

The storage unit 140 stores data for the data processing unit 130 to perform various correction processes.
For example, the storage unit 140 stores white reference data and black reference data. In addition, the storage unit 140
The image data before correction may be stored.

The output unit 150 includes an interface for performing network connection or USB connection, and transmits the digital data output from the data processing unit 130 to the host computer.

The main components of the control unit 100 described above are input / output with a CPU as a main control device, a ROM in which a program and the like are recorded, a RAM that temporarily stores data and the like as a main memory, and a host and the like. This can be achieved by a general computer provided with an interface to be controlled and a system bus serving as a communication path between each component. You may comprise with ASIC (Application Specific Integrated Circuit) designed so that each process may be performed exclusively. The A / D converter 110 is an analog front end IC (Integrated Circuit).
).

The image reading apparatus 10 to which this embodiment is applied has the above-described configuration. However, this configuration is not limited to the above configuration because the main configuration has been described in describing the features of the present invention. Further, other configurations included in a general image reading apparatus are not excluded. Further, the image reading apparatus 10 may be a multifunction machine having a print function and a facsimile function.

In addition, the above-described constituent elements are classified according to main processing contents in order to facilitate understanding of the configuration of the image reading apparatus 10. The present invention is not limited by the way of classification and names of the constituent elements. The configuration of the image reading apparatus 10 can be classified into more components depending on the processing content. Moreover, it can also classify | categorize so that one component may perform more processes. Further, the processing of each component may be executed by one hardware or may be executed by a plurality of hardware.

  Next, image reading control performed in the reading control unit 120 will be described.

FIG. 2 is a timing chart of image reading control (acceleration period) according to an example of an embodiment of the present invention. FIG. 3 shows image reading control (deceleration period) according to an example of an embodiment of the present invention.
It is a timing chart. Note that the output timings of various trigger signals and encoder signals are not limited to the intervals shown.

The reading control unit 120 generates a dummy trigger in addition to the position trigger and the repeat trigger in order to prevent deterioration in image quality when the motor speed is not stable such as the acceleration period and the deceleration period. That is, three shift signals corresponding to RGB colors and one dummy signal are output for each line. Hereinafter, this control method is also referred to as “4-shift control”.

The position trigger is a transfer timing signal that is generated based on an encoder signal that is output according to the rotation of the motor. The repeat trigger is a transfer timing signal generated at a predetermined time interval by a repeat timer (timer unit 121) based on the position trigger. The free run trigger is a transfer timing signal generated at a predetermined time interval by a free run timer (timer unit 121) with reference to a position where it is determined that the motor has stopped. The dummy trigger is a transfer timing signal generated after a predetermined time has elapsed by a dummy timer (timer unit 121) on the basis of the position trigger.

Specifically, the reading control unit 120 periodically monitors the signal state of the encoder signal using the timer unit 121, and generates a predetermined amount that occurs every predetermined amount of rotation of the motor (every two cycles in the illustrated example). When a signal state (in the example shown in the drawing, the upper phase of the encoder signal is H (high) state) is detected, a position trigger is output. The position trigger is a standard color (
In the example shown, it is the charge accumulation start timing corresponding to R) and the transfer timing of the accumulated charge from the timing of the dummy trigger or repeat trigger immediately before the position trigger.

Therefore, as shown in FIG. 2, after starting the motor, T10, T20, T30, T40,
At T50, the position trigger is output. The reading start position is not limited to T10 as long as it is after the start of motor driving. Further, as shown in FIG. 3, T10, T
At 20, T30, T40, T50, T60, a position trigger is output.

In addition, the reading control unit 120 is a repeat trigger that is a charge accumulation start timing corresponding to a color other than the reference color (G and B in the illustrated example) and a charge transfer timing corresponding to the previous color. Is output using a repeat timer (timer unit 121). That is, the reading control unit 120 outputs a repeat trigger corresponding to G when the predetermined interval i has elapsed from the output timing of the position trigger, and further outputs a repeat trigger corresponding to B when the predetermined interval i has elapsed. To do.

Therefore, as shown in FIG. 2, T11, T12, T21, T22, T31, T32, T4
At 1, T42, and T51, a repeat trigger is output. As shown in FIG. 3, T11, T12, T21, T22, T31, T32, T41, T42, T51, T
At 52, T61, and T62, a repeat trigger is output.

Further, after outputting a repeat trigger corresponding to the last color (B in the illustrated example) among the RGB colors, the reading control unit 120 transfers the charge corresponding to the last color under a predetermined condition described later. A dummy trigger that is timing is output. The dummy trigger is also a start timing of accumulation of electric charges (dark part noise) from the dummy trigger to the position trigger immediately after the dummy trigger.

Specifically, the reading control unit 120 determines whether or not a predetermined period Di has elapsed from the position trigger, and determines whether or not the setting value indicating the validity / invalidity of the dummy trigger is valid. A dummy trigger is output when the predetermined period Di has elapsed and the set value is valid. The predetermined period Di can be set to a period obtained by adding an interval between a repeat trigger for transferring G charges in a constant speed period and a position trigger immediately after the predetermined period Di, for example, 3i.

The reading control unit 120 sets the set value to be valid at the timing of starting driving the motor, such as when receiving an instruction to read a document. In the acceleration period after the start of motor driving, the reading control unit 120 measures the motor driving cycle for each cycle interrupt, compares it with a predetermined threshold value, and the motor driving cycle falls below the predetermined threshold value. In addition, the set value is set to be invalid.

From the constant speed period to the deceleration period, the reading control unit 120 compares the motor driving cycle with the predetermined threshold value, and validates the set value when the motor driving cycle exceeds the predetermined threshold value. Set. At the timing when the driving of the motor is stopped, the set value is set to invalid.

The predetermined threshold is whether or not the position trigger interval (cycle) exceeds or is less than the total value of the charge accumulation time of all RGB colors and the image information transfer time corresponding to the last color. It is a value for determining whether or not. The total value can be set to 4i obtained by adding i to the predetermined period Di, for example.

For example, in FIG. 2 and FIG. 3, 2i can be set as the predetermined threshold. That is, in FIG. 2, it can be predicted that the interval I ′ between the position triggers will be less than or equal to the total value 4i by comparing the motor driving cycle measured at the timing of C1 with the predetermined threshold 2i. Further, in FIG. 3, it can be predicted that the interval I ″ between the position triggers exceeds the total value 4i by comparing the motor driving cycle measured at a predetermined C2 timing with a predetermined threshold 2i.

Of course, the predetermined threshold and the total value are examples, and can be adjusted as appropriate.
If the dummy trigger is output until the position trigger interval is equal to or less than the total value, there is a problem that the transfer time of the last color image information is insufficient.
Therefore, the value of the predetermined threshold is set so that it can be determined that the position trigger interval exceeds the total value when the motor driving cycle exceeds the predetermined threshold.

Therefore, as shown in FIG. 2, dummy triggers are output at T13 and T23. Further, as shown in FIG. 3, dummy triggers are output at T43, T53, and T63. That is, the charge accumulated for B is transferred by the dummy trigger. Further, the charge (dark noise) accumulated between the dummy trigger and the next position trigger (or free-run trigger) is transferred by the position trigger (or free-run trigger) next to the dummy trigger.

Here, since the image information transferred by the position trigger (or free-run trigger) next to the dummy trigger is invalid data that does not correspond to any of RGB, the data processing unit 130 discards (discards) this data. Do not treat it as read data. Of course, other functional units may be discarded. When the reading control unit 120 outputs a dummy trigger, the reading control unit 120 notifies the data processing unit 130 that data transferred by the next trigger is invalid.

In addition, the reading control unit 120 is configured such that after the motor driving is stopped, a free-run timer (timer unit 1
21) is used to output a free-run trigger. That is, the reading control unit 120 monitors whether or not the driving of the motor is stopped. When the driving of the motor is stopped, the reading control unit 120 outputs a free trigger at every predetermined interval i from that timing. In the present embodiment, the free-run trigger is a charge transfer timing corresponding to dark part noise.

Therefore, as shown in FIG. 3, a free-run trigger is output at T70 and T71.

Further, the reading control unit 120 switches on / off the light source 210 in accordance with the output timing of the shift signal. However, the reading control unit 120 does not turn on the light source 210 at the timing of the dummy trigger.

That is, the reading control unit 120 turns on the red LED at the position trigger timing, continues lighting for a predetermined time, and then turns off. In addition, the green LED is lit at the timing of the repeat trigger next to the position trigger, and is lit for a predetermined time and then turned off. Further, at the timing of the next repeat trigger, the green LED is turned on, and after the lighting is continued for a predetermined time, it is turned off. On the other hand, at the timing of the dummy trigger, the reading control unit 120 does not turn on the light source 210. Further, the light source 210 is not turned on even at the timing of the free run trigger.

Therefore, as shown in FIG. 2, for example, after the LEDs are lit in the order of R (T10), G (T11), and B (T12), the LEDs are not lit in the dummy trigger (T13). Moreover, as shown in FIG. 3, for example, in the free-run trigger (T70), the LED is not lit.

Actually, the lighting duration of each color LED varies depending on the color. This is because the luminance of the three light sources and the sensitivity of the sensor have differences and variations depending on the colors, and if the lighting duration time is the same, the photoelectrically converted output charge amounts of the respective colors are not equal. Therefore, the lighting duration time is set in advance according to the luminance of the three light sources and the sensitivity of the sensor.

As described above, the image reading apparatus 10 performs the 4-shift control when the motor speed is not stable during the acceleration period, the deceleration period, and the like, and is 3 when the motor speed is stable during the constant speed period. Shift control is performed.

  Next, a characteristic operation flow of the image reading apparatus 10 will be described.

FIG. 4 is a flowchart illustrating processing (reading control processing) executed by the image reading apparatus according to an example of the embodiment of the present invention. This flow will be described by paying attention to processing executed by each trigger.

This flow starts when a predetermined time corresponding to each timer has passed (due to a timer interrupt) by a timer (hereinafter referred to as a position timer) for monitoring the encoder signal, a repeat timer, a dummy timer, or a free-run timer. Is done.

In S <b> 10, the reading control unit 120 determines whether it is the generation timing of the position trigger. Specifically, the reading control unit 120 determines whether or not an interruption by the position timer has occurred. When a position timer interrupt occurs (S10: YES)
), The process proceeds to S20. When no position timer interrupt has occurred (S10
: NO), the process proceeds to S50.

In the case of S10: YES, when a position timer interruption occurs (S10:
YES), the reading control unit 120 determines whether or not the detected encoder signal is in a predetermined signal state. That is, it is determined whether the motor has rotated a predetermined amount. If the encoder signal is in a predetermined signal state, the process proceeds to S20. If the encoder signal is not in a predetermined signal state, this flow ends.

In S <b> 20, the reading control unit 120 generates a shift signal (position trigger) and outputs it to the image sensor 220. Then, the process proceeds to S30.

In S30, the reading control unit 120 performs LED lighting control. Specifically, the reading control unit 1
20 turns on the LED set as the lighting color of the light source 210 for a predetermined time. In this process, the reference red LED is turned on. Then, the reading control unit 120 advances the process to S40.

In S40, the reading control unit 120 sets the next lighting color. Specifically, the reading control unit 120 sets the next lighting color after the color that was lit in S30. In this process, a green LED that is the next color of the reference color is set. Then, the reading control unit 120 ends this flow.

In S50, the reading control unit 120 determines whether or not it is a repeat trigger generation timing. Specifically, the reading control unit 120 determines whether or not an interruption by a repeat timer has occurred. When a repeat timer interrupt occurs (S50: YES),
The process proceeds to S60. When no repeat timer interrupt has occurred (S50: NO)
), The process proceeds to S90.

In S <b> 60, the reading control unit 120 generates a shift signal (repeat trigger) and outputs it to the image sensor 220. Then, the process proceeds to S70.

In S70, the reading control unit 120 performs LED lighting control. Specifically, the reading control unit 1
20 turns on the LED set as the lighting color of the light source 210 for a predetermined time. In this process, the green LED next to the reference color or the blue LED next to the green LED is turned on. Then, the reading control unit 120 advances the process to S80.

In S80, the reading control unit 120 sets the next lighting color. Specifically, the reading control unit 120 sets the next lighting color after the color that was lit in S70. In this process, the green LED
The next blue LED or the red LED (reference color) next to the blue LED is set. And
The reading control unit 120 ends this flow.

In S90, the reading control unit 120 determines whether it is the generation timing of the dummy trigger. Specifically, the reading control unit 120 determines whether or not an interruption by a dummy timer has occurred. If a dummy timer interrupt has occurred (S90: YES), the process goes to S
Go to 100. If the dummy timer interrupt has not occurred (S90: NO), the process proceeds to S140.

In S100, the reading control unit 120 determines whether or not the setting value indicating whether the dummy trigger is valid or invalid is valid. If the set value is valid (S100: YES), the process is S1.
Proceed to 10. If the set value is not valid (S100: NO), this flow ends.

In S <b> 110, the reading control unit 120 generates a shift signal (dummy trigger) and outputs it to the image sensor 220. Then, the process proceeds to S120.

In S120, the reading control unit 120 issues a transfer invalidity notification. Specifically, the reading control unit 1
20 notifies the data processing unit 130 that the data transferred by the next trigger is invalid. Then, the process proceeds to S130.

In S130, the reading control unit 120 sets the next lighting color. Specifically, the reading control unit 120 sets a reference color as the next lighting color. In this process, a red LED is set. Then, the reading control unit 120 ends this flow.

In S140, the reading control unit 120 determines whether it is the generation timing of the free run trigger. Specifically, the reading control unit 120 determines whether or not an interruption by a free run timer has occurred. When a free-run timer interrupt occurs (S140: Y
ES), and the process proceeds to S150. If a free-run timer interrupt has not occurred (
S140: NO), this flow ends.

In S <b> 150, the reading control unit 120 generates a shift signal (free run trigger) and outputs it to the image sensor 220. Then, the process proceeds to S160.

In S160, the reading control unit 120 issues a transfer invalidity notification. Specifically, the reading control unit 1
20 notifies the data processing unit 130 that the data transferred by the next trigger is invalid. Then, this flow ends.

FIG. 5 is a flowchart for explaining processing (periodic interrupt processing) executed by the image reading apparatus according to an example of the embodiment of the present invention. This flow will be described by paying attention to the dummy trigger valid / invalid setting process.

  This flow is started by, for example, a periodic interrupt.

In S210, the reading control unit 120 determines whether or not there has been an instruction to start motor driving. If there is an instruction (S210: YES), the process proceeds to S220. If there are no instructions (
(S210: NO), the process proceeds to S230.

In S220, the reading control unit 120 sets the setting value indicating whether the dummy trigger is enabled / disabled to be valid. Then, this flow ends.

In S230, the reading control unit 120 determines whether the motor driving is stopped. When the motor drive is stopped (S230: YES), the process proceeds to S240. If the motor drive is not stopped (S230: NO), the process proceeds to SS260.

In S240, the reading control unit 120 sets the setting value indicating whether the dummy trigger is valid / invalid. Then, the process proceeds to S250.

In S250, the reading control unit 120 starts a free-run timer. Then, this flow ends.

In S260, the reading control unit 120 measures the driving period of the motor and compares it with a predetermined threshold value. If the motor driving cycle exceeds the predetermined threshold (S260: YES), the process is S
Proceed to 270. When the driving cycle of the motor is not more than the predetermined threshold (S260: NO)
, The process proceeds to S280.

In S <b> 270, the reading control unit 120 sets a setting value indicating whether the dummy trigger is valid / invalid. Then, this flow ends.

In S280, the reading control unit 120 sets the setting value indicating the validity / invalidity of the dummy trigger to invalid. Then, this flow ends.

Each processing unit of each flow in FIGS. 4 and 5 described above is divided according to main processing contents in order to facilitate understanding of the processing of the reading control unit 120. The present invention is not limited by the way of dividing the processing unit or the name. The processing of the reading control unit 120 is performed according to the processing content.
Further, it can be divided into many processing units. Moreover, it can also divide | segment so that one process unit may contain many processes.

The embodiment of the present invention has been described above. According to the present embodiment, it is possible to improve the read image quality when the motor speed is not stable such as the acceleration period and the deceleration period.

That is, according to the present embodiment, the image reading apparatus 10 reads a document by 4-shift control when the motor speed is not stable during an acceleration period, a deceleration period, or the like. With such a configuration, it is possible to further reduce dark part noise and improve image quality.

The above-described embodiment of the present invention is intended to illustrate the gist and scope of the present invention and is not intended to be limiting. Many alternatives, modifications, and variations will be apparent to those skilled in the art.

10: image reading device, 100: control unit, 110: A / D conversion unit, 120: reading control unit, 1
21: Timer unit, 130: Data processing unit, 140: Storage unit, 150: Output unit, 200:
Carriage 210: Light source 220: Image sensor 300: Drive mechanism 310: Motor 320: Encoder

Claims (6)

An image reading device,
An image sensor for transferring the charge accumulated in the photoelectric conversion element to a shift register by a shift signal; a control means for controlling an output timing of the shift signal; a motor for moving a carriage for carrying the image sensor; An encoder that detects and outputs the amount of rotation of the motor,
The control means includes
3 shift control that outputs a shift signal that is the charge accumulation start timing of each RGB color for each line, and a shift signal that is the charge accumulation start timing corresponding to each RGB color for each line, in addition to each RGB color. One of four shift controls for outputting a predetermined dummy shift signal after the output of the shift signal to be performed,
The motor speed is determined based on the output of the encoder, and when the motor speed is equal to or lower than the predetermined speed, the 4-shift control is selected, and when the motor speed exceeds the predetermined speed, the 3-shift control is selected. To
An image reading apparatus. The image reading apparatus according to claim 1,
Processing means for processing an image signal from the image sensor;
The processing means, when the 4-shift control is selected, processes the image signal output from the image sensor by a shift signal corresponding to a predetermined reference color as invalid data.
An image reading apparatus. The image reading apparatus according to claim 1, wherein
It has a light source corresponding to each color of RGB,
In the 4-shift control, the control means
In accordance with the shift signal that is the charge accumulation start timing of each RGB color, the corresponding color light source is turned on, and none of the light sources is turned on with the predetermined dummy shift signal.
An image reading apparatus. The image reading apparatus according to any one of claims 1 to 3,
In the 4-shift control, the control means
When the output result of the encoder is in a predetermined state, a shift signal that is a charge accumulation start timing corresponding to the predetermined reference color is output,
With reference to the charge accumulation start timing corresponding to the predetermined reference color, when a predetermined time has elapsed for each color other than the predetermined reference color, charge accumulation corresponding to each color other than the predetermined reference color is performed. The shift signal that is the start timing is output,
When a predetermined time has elapsed after the output of the shift signal, which is the charge accumulation start timing corresponding to each color other than the predetermined reference color, with reference to the charge accumulation start timing corresponding to the predetermined reference color Outputting the predetermined dummy shift signal;
An image reading apparatus. The image reading apparatus according to any one of claims 1 to 4,
The period during which the 4-shift control is executed includes at least a part of the acceleration period and the deceleration period of the motor.
An image reading apparatus. An image reading control method in an image reading apparatus,
The image reading device includes:
An image sensor that transfers the charge accumulated in the photoelectric conversion element to a shift register by a shift signal, and a motor that moves a carriage that carries the image sensor,
3 shift control that outputs a shift signal that is the charge accumulation start timing of each RGB color for each line, and a shift signal that is the charge accumulation start timing corresponding to each RGB color for each line, in addition to each RGB color. One of four shift controls for outputting a predetermined dummy shift signal after the output of the shift signal to be performed,
Determining the speed of the motor, selecting the 4-shift control if the motor speed is below a predetermined speed, and selecting the 3-shift control if the motor speed exceeds a predetermined speed;
An image reading control method.

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