JP2012169963A - Image reading device, image reading method, and program - Google Patents

Abstract

An image reading apparatus that does not generate a shift pulse unless a predetermined time has elapsed since the last generation of a shift pulse is provided.
An image reading apparatus includes a mechanism driven by a motor, the image reading unit transferring a charge accumulated in a photoelectric conversion element by a shift pulse, and a shift pulse based on rotation of the motor. A shift pulse control unit that controls the output timing of the output of the shift pulse, and the shift pulse control unit outputs the shift pulse when the specified time required for charge transfer has not elapsed since the last output of the shift pulse. The output is postponed and stored as a shift pulse to be output later.
[Selection] Figure 1

Description

  The present invention relates to an image reading apparatus, an image reading method, and a program.

Some image reading apparatuses such as image scanners have an ADF (Auto Document Feeder) function and read image data of a document by an image sensor stationary at a predetermined position while the document is conveyed by the ADF at a constant speed.

In such an image reading apparatus, a shift pulse is generated according to the amount of rotation of a motor that transports a document by ADF. And the electric charge accumulated in the light receiving part of the image sensor,
The shift pulse is shifted to the shift register and sequentially transferred to the controller (for example, Patent Document 1).

However, in order to secure the transfer time to the controller, even if it is the timing to generate the shift pulse, the shift pulse cannot be generated unless the predetermined time has elapsed since the last shift pulse was generated. ing.

JP 2009-246636

In the image reading apparatus as described above, the document reading speed may be higher than expected. In such a case, even if it is time to generate the shift pulse, the shift pulse cannot be generated because a predetermined time has not elapsed since the previous shift pulse was generated. As a result, the read image is lost.

SUMMARY OF THE INVENTION An object of the present invention is to provide a technique for preventing a missing image from occurring in an image reading apparatus as described above.

The present invention for solving the above problems is an image reading apparatus having a mechanism driven by a motor, wherein an image reading unit that transfers charges accumulated in a photoelectric conversion element by a shift pulse, and rotation of the motor. And a shift pulse control unit for controlling the output timing of the shift pulse, and the shift pulse control unit has passed a specified time necessary for transferring the charge since the last output of the shift pulse. If not, the output of the shift pulse is postponed and stored as a shift pulse to be output later.

2 is a block diagram illustrating an example of a schematic configuration of an image reading apparatus 50 according to the present embodiment. FIG. 6 is a timing chart for explaining an overview of image reading control of the present embodiment. It is a flowchart for demonstrating the pre-process in the image reading control of this embodiment. 5 is a flowchart for explaining main processing in image reading control of the present embodiment. It is a timing chart for demonstrating the outline | summary of the conventional image reading control.

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

FIG. 1 is a block diagram illustrating an example of a schematic configuration of an image reading apparatus 50 to which an embodiment of the present invention is applied.

The image reading device 50 is a so-called flat bed type image reading device having a document table (not shown) on the upper surface of a housing. The image reading device 50 scans the image sensor 220 and reads an image of a document placed on a document platen of a transparent plate. The image reading apparatus 50 is not limited to a scanner, and may be a facsimile, a copier, a multifunction machine, or the like having a scanning function.

The image reading apparatus 50 has an upward document table (not shown) for placing a document as a medium to be read.
And a cover (not shown) for covering the document placement surface (board surface) and the image reading window of the document table from above. The lid is coupled to the document table via a hinge mechanism and can be opened and closed.

Also, an ADF (paper feeder) 300 is provided on the upper side of the image reading window integrally with the lid. The ADF 300 includes a DC motor 310, a paper feed tray (not shown), a transport roller (not shown), a paper discharge tray (not shown), and the like. Here, the rotation of the transport roller is D
Controlled by C motor 310. The ADF 300 can pass the document placed on the paper feed tray by feeding it to the upper surface of the image reading window. DC motor 3
10 includes a first encoder that outputs a pulse according to the rotation amount of the conveyance roller (that is, the conveyance amount of the document).

Further, as shown in the figure, the image reading apparatus 50 includes a carriage 200 on which an LED light source 210 and an image sensor (for example, a CCD color image sensor) 220 are mounted under a document table. Further, the image reading device 50 includes a carriage driving mechanism (not shown) that controls the reciprocation of the carriage 200, and a controller 100 that controls the entire image reading device 50 and performs various processes for reading an image. I have.

The carriage 200 carries the image sensor 220 in the sub-scanning direction. Carriage 2
00 is slidably mounted on a guide shaft parallel to the platen surface of the document table and the image reading window, and is reciprocated by being pulled by a belt rotated by a motor of a carriage drive mechanism. The movement amount of the carriage 200 is controlled by the output value of the second encoder that outputs a pulse in accordance with the rotation amount of the motor of the carriage drive mechanism.

That is, the carriage drive mechanism includes a motor for rotating a belt attached to the carriage and an encoder that outputs a pulse in accordance with the rotation amount of the motor.

In the case where reading is performed while the original is conveyed by the ADF 300, the carriage 20
0 is fixed at a predetermined position under the image reading window.

The LED light source 210 includes a red (R) LED, a green (G) LED, and a blue (B) LED, and generates light of three colors of RGB in a predetermined order. In this embodiment, the LED light source 210 is
When reading one line of a normal document, red LED, green LED, blue LE
Light is generated in the order of D. A similar light emitting operation is repeated in order to read the number of lines necessary for generating image data of the document. The light emission time of each color LED is predetermined for each color, and is extinguished when the predetermined time elapses after lighting. In addition, lighting of the LED light source 210 of each color is performed by supplying a predetermined current (current from a main control unit 110 described later).

The image sensor 220 receives the light reflected from the document, accumulates electric charges corresponding to the amount of received light, and sends it to the controller 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 is a regular CIS (Contact Image Sensor) or CCD (Charge Coupled Dev).
ice) It has the same configuration as an image sensor. That is, each sensor chip includes a photoelectric conversion element (photodiode), 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 shift pulse (a signal from the main control unit 110 described later). Since the photoelectric conversion element always accumulates charges according to the amount of light received, the charge transfer timing to the shift register is the start timing for accumulating charges for the next light of the emission color. The charge transferred to the shift register is
From the output part at the end of the shift register, it is converted into an electrical signal (analog data), and A /
It is sent to the D converter 120.

The output of the charge stored in the shift register is performed in response to a predetermined read clock (a signal from the main control unit 110 described later). For example, the charge of one pixel is output as analog data every clock.

The controller 100 includes an A / D conversion unit 120 that converts analog data output from the image sensor 220 into digital data, and a data processing unit 130 that performs various corrections on the digital data output from the A / D conversion unit 120. And a storage unit 140 for storing correction data (white reference data and black reference data) used for various corrections by the data processing unit 130, read data (image data) to be corrected, and data from the data processing unit 130 An output unit 150 for sending the data to a host such as a personal computer, and the controller 100
Each of the functional units is controlled overall, and an LED light source 210 and an image sensor 220 in the carriage 200 and a main control unit 110 for controlling the carriage driving mechanism are provided.

The A / D conversion unit 120 is realized by, for example, AFE (Analog Front End), and converts analog data output from the image sensor 220 into digital data.

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.

The data processing unit 130 can be configured by a computer including a CPU that is a main control device, a ROM that stores programs and the like, and a RAM that temporarily stores data and the like as a main memory. Of course, the data processing unit 130 may be configured by an ASIC (Application Specific Integrated Circuit) designed to perform various correction processes exclusively.

The storage unit 140 is realized by a buffer, for example. The storage unit 140 temporarily stores the digital data output from the A / D conversion unit 120 in a first-in first-out FIFO format, and sends the data to the output unit 150 in order from the previously stored data.

The output unit 150 is realized by an interface for performing network connection or USB connection. The output unit 150 transmits the data in the storage unit 140 to the host computer (scanner control device) at a transfer rate according to the processing capability of the host.

The main control unit 110 includes an ADF 300, a carriage 200, and a carriage driving mechanism (
(Not shown) is controlled to read an image (“image reading control” is performed). Specifically, the main control unit 110 includes a motor control unit 111 and a reading control unit 11 as illustrated.
2 and.

The motor control unit 111 controls (PID control) the DC motor (drive motor) 310 of the ADF 300 to convey the document on the paper feed tray and pass it through the image reading window. For example, the motor control unit 111 can drive the DC motor 310 at a constant speed.

The motor control unit 111 controls a reciprocating movement of the carriage 200 by controlling a motor (not shown) of the carriage driving mechanism. For example, the motor control unit 111 can drive the carriage 200 at a constant speed.

The reading control unit 112 controls image reading by the image sensor 220. Specifically, the reading control unit 112 rotates the DC motor 310 of the ADF 300 (that is, the output value of the first encoder) or rotates the motor of the carriage drive mechanism (that is, the output value of the first encoder).
The shift pulse is output to the image sensor 220 based on the output value of the second encoder.

FIG. 2 is a timing chart for explaining the outline of the image reading control.

As shown in the figure, for example, when reading an image using the ADF 300, the reading control unit 112 sets the output value (current position) of the first encoder to a set value (in the example shown, “4 ×
(Integer N) -1 ") (for example, ENC A falling timing), shift pulse output scheduled timing (shown as" A "," B ", ...," M "position) ). Further, when the reading control unit 112 reads a document placed on the document table without using the ADF 300, the output value (current position) of the second encoder is set to a set value (in the example shown, “4 × (integer). N) -1 ”) (for example, the falling timing of ENC A) is a shift pulse output scheduled timing (“ A ”,“ B ”,.
, “M” position).

However, the reading control unit 112 does not pass the specified shift time since the last output of the shift pulse even when the shift pulse is scheduled to be output ("A", "
E ”,“ F ”,“ G ”,“ H ”,“ I ”,“ J ”,“ K ”,“ L ”,“ M ”), the output of the shift pulse is postponed and output later. It is stored as a power shift pulse (for example, the output remaining number of shift pulses is incremented). The prescribed shift time is a minimum time required for the charge (for example, one line) accumulated in the photoelectric conversion element of the image sensor 220 to be transferred to the controller 100 through the shift register. Also,
The elapsed time after outputting the shift pulse is measured using a predetermined timer.

Further, the read control unit 112 outputs a shift pulse when the shift pulse is scheduled to be output and the specified shift time has elapsed since the last output of the shift pulse (" A '","B'"," C '","D'"," E '","G'","
I ′ ”,“ J ′ ”,“ K ′ ”,“ L ′ ”). At this time, the reading control unit 112 decrements the remaining number of output of the shift pulse and resets a timer that measures an elapsed time after outputting the shift pulse.

By the way, as in the example shown in FIG. 2, the DC motor 310 of the ADF 300 or the motor of the carriage drive mechanism may be faster than expected (for example, timing D
To timing I). In such a case, of course, the interval (hereinafter referred to as “scheduled shift period T”) from when the shift pulse is output last time to when the next shift pulse is scheduled to be output becomes short.

Then, there is a case where the shift pulse cannot be output even once within the period of the scheduled shift period T (the period from F to G and the period from H to I in the shaded portion shown in the figure).

Normally, if the shift pulse is not output once within the period of the scheduled shift period T (that is, at each scheduled output timing of the shift pulse), the read image is lost.

Therefore, when the reading control unit 112 according to the present embodiment can output the shift pulse later so that the read image is not lost even if the shift pulse cannot be output even once within the period of the scheduled shift period T. A shift pulse is output to.

Specifically, as shown in FIG. 2, the reading control unit 112 can output an additional shift pulse within the period of the scheduled shift period T (for example, a period from J to K in the illustrated dot portion). Then, a shift pulse that has been postponed in the past (postponed at timing F) is output ("F '" shown in the figure). Of course, also in this case, the reading control unit 112 decrements the remaining output number of the shift pulse and resets a timer that measures an elapsed time after the output of the shift pulse.

In this way, the reading control unit 112 according to this embodiment outputs a shift pulse by finding a timing that can be output even when the DC motor 310 of the ADF 300 or the motor of the carriage driving mechanism is faster than expected. Therefore, there is no loss in the read image.

Note that the reading control unit 112 outputs the image sensor 220 at the output timing of the shift pulse.
Is supplied with a read clock, and the output of the charge stored in the shift register to the controller 100 (A / D converter 120) is controlled.

At this time, the data (analog data) output from the image sensor 220 is A /
The data is converted into digital data by the D conversion unit 120, and various corrections are performed by the data processing unit 130.

Then, the reading control unit 114 notifies the data processing unit 130 of an instruction signal, and stores (buffers) the data subjected to various corrections in the storage unit 140.

Further, the reading control unit 114 keeps the carriage 200 stopped under the image reading window when reading an original using the ADF 300.

The main control unit 110 includes a computer that includes a CPU that is a main control device, a ROM that stores programs and the like, and a RAM that temporarily stores data and the like as a main memory. However, it can also be configured by hardware (for example, ASIC) designed to perform each process exclusively.

The image reading apparatus 50 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 A / D conversion unit 120 may be mounted on a substrate in the carriage 200.

Each of the above-described constituent elements is classified according to the main processing contents in order to facilitate understanding of the configuration of the image reading apparatus 50. The present invention is not limited by the way of classification and names of the constituent elements. The configuration of the image reading device 50 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, a characteristic operation of the image reading apparatus 50 configured as described above will be described.

<Pre-processing in image reading control>
FIG. 3 is a flowchart for explaining preprocessing in image reading control.

The reading control unit 112 starts this flow at a predetermined timing. For example, the reading control unit 1
No. 12 starts this flow when an instruction to start reading a document is given.

When this flow is started, the reading control unit 112 initializes parameters for performing image reading control (step S101). Specifically, the reading control unit 112 initializes a position (a setting value of the first encoder or the second encoder) where a shift pulse is to be output first (“3” in the example shown in FIG. 2). Further, the reading control unit 112 resets the remaining number of output shift pulses (“0” in the illustrated example). Further, the reading control unit 112 sets a specified shift time (minimum time necessary for the charge accumulated in the photoelectric conversion element of the image sensor 220 to be transferred to the controller 100).

After initializing parameters for performing image reading control, the reading control unit 112 ends this flow.

The reading control unit 112 according to the present embodiment can appropriately read an image by performing the processing of the above flow prior to image reading control.

<Main processing in image reading control>
FIG. 4 is a flowchart for explaining main processing in image reading control.

The reading control unit 112 starts image reading control after the above preprocessing is completed. When the image reading control is started, the motor control unit 111 includes the DC motor 310 of the ADF 300,
Alternatively, driving of the motor of the carriage driving mechanism is started. Here, the DC motor 310
Or, depending on the amount of rotation of the motor of the carriage drive mechanism, the current position of document reading (
That is, the output value of the first encoder or the output value of the second encoder) changes (in the example shown in FIG. 2, it increases).

Then, the reading control unit 112 starts this flow at a predetermined timing after the image reading control is started. For example, the reading control unit 112 starts this flow repeatedly at a predetermined interval (for example, every several ms). Alternatively, the reading control unit 112 may start this flow every time the current position of document reading changes.

When this flow is started, first, the reading control unit 112 specifies the current position of document reading (that is, the output value of the first encoder or the output value of the second encoder) (step S201).

Then, the reading control unit 112 determines whether or not the current position specified in step S201 is a position where the shift pulse is to be output (the above-described “shift pulse output scheduled timing”) (step S202). Specifically, the reading control unit 112 sets the current position specified in step S201 and a value set as a position (shift pulse output scheduled timing) at which a shift pulse is to be output (for example, set in the above preprocessing). The set value). Then, the reading control unit 112 determines that the current position is a position where a shift pulse should be output (for example, “4
X (integer k) -1 "), it is determined that the position where the shift pulse should be output. On the other hand, the reading control unit 112 determines that the current position is to output a shift pulse (for example, “
4 × (integer k) −1 ”) is not reached, it is determined that the position is not to output the shift pulse.

Here, if it is determined that the position where the shift pulse is to be output (step S202; Y
es), the reading control unit 112 sets a position where a shift pulse is to be output next time (step S203). For example, the reading control unit 112 sets the setting value of the first encoder or the second encoder to “4 × (integer k + 1) −1”.

Further, the reading control unit 112 increments the remaining number of output shift pulses (hereinafter, the remaining number of shift pulses to be output) and stores it in a predetermined storage device (step S204). In addition,
The processes in steps S203 and S204 are performed at timings “A” to “M” in the example illustrated in FIG.

  Thereafter, the reading control unit 112 moves the process to step S205.

On the other hand, if it is determined in step S202 that the position is not to output the shift pulse (step S202; No), the reading control unit 112 performs steps S203 and S2.
The process of 04 is omitted and the process proceeds to step S205.

When the process proceeds to step S205, the reading control unit 112 determines whether or not the specified shift time (the specified shift time set in the above preprocessing) has elapsed since the shift pulse was output last time ( Step S205). Specifically, the reading control unit 112 acquires the value of the timer that measures the elapsed time from when the shift pulse was output last time, and determines whether or not the specified shift time has elapsed. However, at the timing of outputting the first shift signal (current position “3” in the example shown in FIG. 2), there is no previous shift pulse, and thus the elapsed time since the last shift pulse was output cannot be measured. Therefore, the determination of step S205 is not performed at the timing of outputting the first shift signal, but the determination of step S205 is performed at the timing of outputting the second and subsequent shift signals (in the example shown in FIG. 2, after the current position “7”). carry out.

Here, when the specified shift time has elapsed, the reading control unit 112 (step S2).
Next, it is determined whether or not the remaining number of output of the shift pulse is “1” or more (step S206). Specifically, the reading control unit 112 reads the number of remaining shift pulses from a predetermined storage device (for example, a counter), and determines whether or not the read value is “1” or more.

Then, the reading control unit 112 (when the output remaining number of shift pulses is “1” or more) (
(Step S206; Yes), the shift pulse is output to the image sensor 220 (Step S207). In the example illustrated in FIG. 2, the process of step S207 is performed at timings “A ′” to “G ′”, “I ′” to “L ′”, and the like.

Of course, the read control unit 112 supplies a read clock to the image sensor 220 at the output timing of the shift pulse here, and the charge controller 100 (A / D conversion unit 120) stored in the shift register. Start transferring to.

Then, the reading control unit 112 decrements the remaining number of shift pulses and stores it in a predetermined storage device (step S208). The reading control unit 112 resets a timer that measures an elapsed time after outputting the shift pulse every time the shift pulse is output.

  Thereafter, the reading control unit 112 ends this flow.

On the other hand, when it is determined in step S205 that the specified shift time has not elapsed (step S205; No), or in step S206, the reading control unit 112 determines that the remaining number of output shift pulses is “0” (step S205). In S206; No), the output of the shift pulse is postponed, and this flow ends. In the example shown in FIG. 2, timings “A”, “D” to “J”,
This flow is terminated without outputting a shift pulse at “L”, “M” or the like.

As described above, the image reading apparatus 50 according to the present embodiment has passed the specified shift time since the last output of the shift pulse, even when the shift pulse is scheduled to be output (step S202; Yes). If there is not (the above step S205; No), the output of the shift pulse is postponed and stored as a shift pulse to be output later (the above step S2).
04).

At the same time, the image reading apparatus 50 according to the present embodiment, according to the remaining output number of the shift pulse, if the specified shift time has elapsed since the last output of the shift pulse (step S205; Yes). (Step S206; Yes), the shift pulse can be output any number of times within the period of the scheduled shift cycle T (Step S207, timings “J ′” and “F ′” in the example shown in FIG. 2).

For this reason, the image reading apparatus 50 according to the present embodiment can output the shift pulse later even if the document reading speed becomes higher than expected and the shift pulse cannot be output at the scheduled timing. . As a result, no loss occurs in the read image.

Note that each processing unit of the flow in the above embodiment is divided according to the main processing contents in order to make the image reading device 50 easy to understand. The invention of the present application is not limited by the method of classification of the processing steps and the names thereof. The processing performed by the image reading device 50 can be divided into more processing steps. One processing step may execute more processes. Further, the order of the processing steps is not limited to this, and can be changed as much as possible.

Moreover, said embodiment intends to illustrate the summary of this invention, and does not limit this invention. Many alternatives, modifications, and variations will be apparent to those skilled in the art.

In the following, conventional image reading control will be described for reference. FIG. 5 is a timing chart for explaining an outline of conventional image reading control.

As shown in the figure, in the conventional image reading control, the output timing “A” of the shift pulse is scheduled.
Even if “M”, if the specified shift time has not elapsed since the last output of the shift pulse, the shift pulse is output after the specified shift time has elapsed.

However, unlike the image reading apparatus 50 of the present embodiment, when the shift pulse cannot be output even once within the period of the scheduled shift period T (the period from F to G in the shaded portion shown in FIG. The shift pulse that could not be output during the period until I) cannot be output later. Therefore, in the conventional image reading apparatus 50, the read image is lost.

On the other hand, in the image reading control of the above embodiment of the present application, even if the shift pulse cannot be output even once within the period of the scheduled shift period T by maintaining the output number of shift pulses. Can be output later. For this reason, the read image is not lost.

50... Image reading device, 100... Controller, 110.
DESCRIPTION OF SYMBOLS 11 ... Motor control part, 112 ... Reading control part, 120 ... A / D conversion part, 13
DESCRIPTION OF SYMBOLS 0 ... Data processing part, 140 ... Memory | storage part, 150 ... Output part, 200 ... Carriage, 210 ... LED light source, 220 ... Image sensor, 300 ... ADF,
310 ... DC motor

Claims (5)

An image reading apparatus having a mechanism driven by a motor,
An image reading unit for transferring the charge accumulated in the photoelectric conversion element by a shift pulse;
A shift pulse controller that controls the output timing of the shift pulse based on the rotation of the motor, and
The shift pulse controller is
If the specified time required for the charge transfer has not elapsed since the last output of the shift pulse, the output of the shift pulse is postponed and stored as a shift pulse to be output later.
An image reading apparatus. The image reading apparatus according to claim 1,
The shift pulse controller is
If an additional shift pulse can be output between the time when the shift pulse is output and the time when the next shift pulse is scheduled to be output, the postponed shift pulse is output.
An image reading apparatus. The image reading apparatus according to claim 2,
Further equipped with a shift output remaining number counter,
Incrementing the shift output remaining number counter at the timing when the output of the shift pulse is scheduled,
When the specified time has elapsed and the shift output remaining number counter is 1 or more, a shift pulse is output and the shift output remaining number counter is decremented.
An image reading apparatus. An image reading method in an image reading apparatus having a mechanism driven by a motor,
An image reading step of transferring the charge accumulated in the photoelectric conversion element by a shift pulse;
A shift pulse control step for controlling the output timing of the shift pulse based on the rotation of the motor, and
In the shift pulse control step,
If the specified time required for the charge transfer has not elapsed since the last output of the shift pulse, the output of the shift pulse is postponed and stored as a shift pulse to be output later.
An image reading method. A program for causing a computer to function as an image reading device having a mechanism driven by a motor,
An image reading step of transferring the charge accumulated in the photoelectric conversion element by a shift pulse;
A shift pulse control step for controlling the output timing of the shift pulse based on the rotation of the motor;
In the shift pulse control step,
If the specified time required for the charge transfer has not elapsed since the last output of the shift pulse, the output of the shift pulse is postponed and stored as a shift pulse to be output later.
A program characterized by that.

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