JP2008065217A - Scanner apparatus, printer, and scanning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a scanner apparatus that can drive a carriage at low noise, as well as, at a desired speed. <P>SOLUTION: The scanner apparatus that scans a predetermined object to be scanned and generates an image data includes an image sensor 20 that converts the light image of the object to be scanned into corresponding image data; a moving means (DC motor 26) for moving the carriage that has the image sensor in the subscanning direction; a first control means (DC motor control unit 513) for controlling the moving means by the first control processing; a second control means (DC motor control unit 513) for controlling the moving means by the second control processing that is different from the first control processing; and a selection means (CPU 501) that selects the first or the second control means, according to the settings related to scanning. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a scanner device, a printing device, and a scanning method.

  2. Description of the Related Art Conventionally, there has been known a scanner device that scans a predetermined scanning object (hereinafter referred to as “original”) to create image data (see Patent Document 1 below). The carriage of this scanner device includes a light source and emits light from the light source. The light emitted from the light source is applied to the document, and forms an irradiation area (hereinafter referred to as a scanning location). In addition, reflected light is generated from the scanned portion, and this reflected light is incident on the image sensor. The image sensor accumulates the reflected light for a predetermined time, and converts the accumulated reflected light into an electrical signal, thereby generating image data of a portion of the original whose scanning portion has moved within the predetermined time when the reflected light is accumulated. The carriage is transported in the scanning direction by a carriage transport mechanism using a predetermined motor as a drive source, and the scanning location moves together with the carriage.

  Based on the resolution in the scanning direction designated by the user or the like, the scanner device sets a plurality of lines having a density corresponding to the resolution in the area to be scanned on the document. Each of these lines is formed in a strip shape and is set to be parallel in the scanning direction. Then, when the scanner device transports the carriage in the scanning direction, the scanning position moves along each line. At this time, the scanner device causes the image sensor to start storing reflected light when the scanning point comes to the start point of each line, and causes the image sensor to stop storing reflected light when the scanning point reaches the end point of the line. The image sensor generates image data of the line (hereinafter referred to as line image data). In this case, for example, in each line, the scanner device drives the motor so as to convey the carriage in the scanning direction so that the time during which the scanning portion passes through each line is a predetermined time. ing.

JP 2004-282561 A

  By the way, when driving a carriage, a stepping motor is generally used in many cases. However, the stepping motor has a problem that the operation sound is louder than that of the DC motor.

  Therefore, it is conceivable to drive the carriage using a DC motor. The rotation speed of the motor is controlled by adjusting the drive voltage applied to the motor. For example, in the case of a DC motor, an extremely small drive voltage is applied to the motor in order to rotate at a very slow speed. By the way, the motor has a voltage range (dead zone) in which it does not rotate because the torque obtained according to the drive voltage is smaller than the static friction force. The carriage conveying motor is a DC motor, and as described above, if a very small driving voltage is applied to the DC motor in order to increase the reading resolution, the driving voltage corresponds to the range of the dead zone. There is a problem that it may not rotate.

  The present invention has been made based on the above circumstances, and an object of the present invention is to provide a scanner device, a printing device, and a scanning method capable of driving a carriage at a desired speed with low noise. It is intended to provide.

  In order to achieve the above object, a scanner device of the present invention is a scanner device that scans a predetermined scan object to generate image data, and converts an optical image of the scan object into corresponding image data. A sensor, a moving means for moving a carriage having an image sensor in the sub-scanning direction, a first control means for controlling the moving means by a first control process, and the moving means are different from the first control process. A second control unit that controls the second control process; and a selection unit that selects the first or second control unit according to the setting content related to the scan. Therefore, it is possible to provide a scanner device that can drive the carriage at a desired speed with low noise.

  In addition to the above-described invention, in the scanner device of another invention, the moving means has a DC motor for moving the carriage in the sub-scanning direction. For this reason, it is possible to provide a scanner device with low noise and low noise.

  In addition to the above-described invention, in the scanner device of another invention, the first control unit performs control according to the position of the carriage, and the second control unit performs control according to the position and speed of the carriage. The selection means selects the first control means when moving the motor of the movement means at a predetermined speed or less, and selects the second control means in other cases. . For this reason, by switching between the first control and the second control according to the speed, the carriage can be controlled by control optimal for each speed.

  According to another aspect of the invention, in addition to the above-described invention, the first control unit is driven so that the motor included in the moving unit rotates intermittently, and the second control unit includes the moving unit. The selection means selects the first control means when the motor included in the movement means is moved at a predetermined speed or less, and the second means otherwise selects the second control means. The control means is selected. For this reason, for example, even if the speed is lower than the dead zone of the motor, it can be driven by intermittent operation, and can be efficiently controlled by the second control when moving at a high speed.

  In addition to the above-described invention, in the scanner device of another invention, the selection unit selects the first and second control units according to the resolution of the image data to be obtained or monochrome / color. I have to. For this reason, it is possible to select the optimal control according to the resolution or monochrome / color, and to read the scan object.

  The printing apparatus of the present invention includes the scanner device described above. Therefore, it is possible to provide a printing apparatus that can drive the carriage at a desired speed with low noise.

  The scan method of the present invention is a scan method for generating image data by scanning a predetermined scan object, and is different from the first control process according to the setting content related to the scan. Control process 2 is selected, and control is performed to move the carriage having an image sensor that converts the optical image of the scan target into corresponding image data. Therefore, it is possible to provide a scanning method that can drive the carriage at a desired speed with low noise.

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

  FIG. 1 is a perspective view showing a configuration example of a printing apparatus 10 using a scanner device according to an embodiment of the present invention. As shown in FIG. 1, a printing apparatus 10 is a so-called composite printing apparatus in which a scanner device, a printing device, and a copying device are integrated. Here, the printing apparatus 10 includes a case 11 that covers the entire apparatus, a paper feeding device (not shown) that supplies printing paper, a scanner device that includes a transparent contact glass 13 on which a document is placed, a carriage 14, and the like. And a printing unit (not shown) for printing on the printing paper. The operation of the scanner device of the present invention will be described as the operation of the printing apparatus 10. The scanning method of the present invention will be described as the operation of the printing apparatus 10.

  The case 11 is a substantially rectangular box, and a lid 12 that can be freely opened and closed is provided on the upper portion thereof. When the lid 12 is opened, the contact glass 13 on which the document is placed appears. Inside the contact glass 13 is a carriage 14 provided with an image sensor to be described later. By moving the carriage 14 in the sub-scanning direction, information printed on the document is read as image data. The scanner device is a so-called flat bed type (original fixed type) scanner that reads a fixed original while the image sensor moves in the sub-scanning direction.

  An LCD (Liquid Crystal Display) 15 and various operation buttons 16 are provided at the center of the front surface of the case 11. The LCD 15 displays the menu, operation content, operation status, error content, and the like of the printing apparatus 10, and the operation button 16 is pressed when selecting the menu of the printing apparatus 10.

  The case 11 is provided with a discharge port 17 in the lower part of the front surface so that printed printing paper can be discharged. In addition, a card slot 18 is provided in the central portion on the right side of the front surface of the case 11 so that, for example, a memory card M for recording image data taken by a digital camera (not shown) can be removably stored. It has become. In this example, the card slot 18 is provided with a lid portion 18a. When the memory card M is inserted, the lid portion 18a is opened and closed. The memory card M stores image data compressed by, for example, the JPEG format as a lossy compression method or the TIFF format as a lossless compression method.

  A paper feeding device (not shown) is provided on the back side of the case 11, stocks printing paper, and supplies the printing paper 10 one by one as needed.

  FIG. 2 is a diagram illustrating a detailed configuration example of the scanner device illustrated in FIG. 1. In this figure, the carriage transport mechanism meshes with a DC motor 26 that is a direct current (DC) motor as a moving means, a worm gear 25 joined to the output shaft of the DC motor 26, and the worm gear 25, and rotates at a predetermined reduction ratio. A spur gear 23a, a pulley 23b joined to the spur gear 23a, a timing belt 22 stretched between the pulley 23b and the pulley 21 and partially fastened to the carriage 14, and the carriage 14 in the sub-scanning direction And a guide rail 24 for transporting to the vehicle. The carriage 14 is conveyed in the sub-scanning direction along the guide rail 24 when the DC motor 26 is rotated and the timing belt 22 is driven. In the following description, the distance that the carriage 14 moves when the DC motor 26 rotates once is referred to as a movement distance L.

  An image sensor 20 is provided on the carriage 14. The image sensor 20 is a contact image sensor (CIS) type image sensor, and corresponds to a CCD (Charge Coupled Devices) (not shown) having light receiving elements arranged in a scanning direction at a predetermined pixel density, and to each light receiving element. Lens (not shown), and an LED (Light Emitting Diode) at the time of unillustrated that irradiates the original surface with light of each color of R, G, B. Each light receiving element receives reflected light from the document surface, accumulates electric charge, and outputs it as a signal.

  The encoder 28 is a rotary encoder, and includes a disk 27 joined to the output shaft 26 a of the DC motor 26, and a light emitting diode 28 a and a photodiode 28 b installed so as to sandwich the disk 27.

  The disk 27 is provided with slits (not shown) cut at predetermined intervals along the circumference, and the photodiode 28b can receive light emitted from the light emitting diodes 28a through the slits. Therefore, when the disk 27 rotates with the rotation of the DC motor 26, the photodiode 28b receives light emitted from the light emitting diode 28a at the slit portion and does not receive light at portions other than the slit. As a result, the photodiode 28b generates a number of pulses (hereinafter referred to as “encoder pulse”) corresponding to the number of rotations of the DC motor 26, and the encoder 28 outputs it to the outside.

  Although not shown, there are two sets of the light emitting diodes 28a and the photodiodes 28b, and they are installed so that encoder pulses whose phases are shifted from each other by π / 2 are output from the respective photodiodes 28b. Therefore, the encoder control unit 512, which will be described later, can detect the rotation direction of the DC motor 26 from the encoder 28 based on the change in the phase of these encoder pulses.

  FIG. 3 is a diagram showing a schematic configuration of the control circuit 500 shown in FIG. As shown in FIG. 3, the control circuit 500 mainly includes a CPU 501, a memory 502, a memory I / F (Interface) 503, an external I / F 504, a printer unit 505, an internal I / F 507, and a predetermined ASIC (Application Specified Integrated Circuit) 510 which is an integrated circuit.

  The memory 502 includes a ROM (Read Only Memory) and a RAM (Random Access Memory). The memory 502 stores an image data storage unit 502a that stores image data generated by reading a document, an image data creation operation, and a predetermined program. A work area 502b for performing a deployment work and the like.

  The CPU 501 serving as a selection unit performs various controls for controlling the entire printing apparatus 10 by executing a predetermined program stored in the memory 502 on the work area 502b. Further, the CPU 501 inputs resolution information representing the reading resolution (dpi) of the document, color / monochrome information, and a scanning area (hereinafter referred to as a scanning area) in the document, which is input by the user operating the operation button 16. The scanning area information indicating the calling) is received via the internal I / F 507 and transferred to the ASIC 510. Note that the resolution information includes a resolution in the main scanning direction and a resolution in the sub-scanning direction.

  The memory I / F 503 is an interface for reading image data recorded in the memory card M and writing image data to the memory card M. The external I / F 504 is an interface for connecting to a personal computer or other image input device (for example, a digital camera). The printer unit 505 ejects color ink from the nozzles according to the image data supplied from the CPU 501, and prints a color image on printing paper. The internal I / F 507 is an interface for inputting information generated by the user operating the operation buttons 16.

  The ASIC 510 includes a predetermined integrated circuit, and includes an image sensor control unit 511, an encoder control unit 512, and a DC motor control unit 513, and executes a reading process described later. The image sensor control unit 511 controls the image sensor 20 to accumulate the reflected light so as to have a suitable accumulation time T, and inputs an electrical signal output from the image sensor 20 to convert it into a gradation value. Further, the image sensor control unit 511 creates document image data from line image data of each line described later.

  The image sensor control unit 511 includes a timer 511a. The image sensor control unit 511 measures the time by the timer 511a, controls the lighting time of the LED, and controls the suitable charge accumulation period.

  The encoder control unit 512 detects the encoder pulse output from the encoder 28, and detects the moving distance of the carriage 14 in the scanning direction from the number of encoder pulses detected, the number of slits in the disk 27, and the moving distance L. The encoder control unit 512 detects the rotation direction of the DC motor 26. Therefore, the encoder control unit 512 detects the position of the carriage 14 relative to a certain position in the scanning direction based on the detected movement distance (based on the number of encoder pulses) of the carriage 14 and the rotation direction of the DC motor 26. be able to.

  The DC motor control unit 513 serving as the first control unit and the second control unit supplies DC power supplied from a power supply unit (not shown) to the DC motor 26 and controls the supplied voltage or current. The rotational speed of the DC motor 26 is controlled. Then, the DC motor control unit 513 performs control of the drive voltage (or drive current) by PWM (Pulse Width Modulation) control. That is, the DC motor control unit 513 turns off and on a power control transistor (not shown) every predetermined switching period (for example, 50 μs), and sets the ratio (duty ratio) of the on period to the switching period as a drive voltage or Vary according to drive current. In this way, the on-time is shortened by reducing the duty ratio to lower the driving voltage (or driving current), and the on-time is lengthened by increasing the duty ratio to drive voltage (or driving current). ). The DC motor 26 can be driven by controlling either the voltage or the current. Hereinafter, the case where the voltage is controlled will be described as an example.

  FIG. 4 is a graph showing the relationship between the drive voltage and the rotation speed in the DC motor 26. In the graph shown in FIG. 4, the horizontal axis represents the drive voltage, and the vertical axis represents the rotation speed. For convenience of explanation, a part of the range where the drive voltage is smaller than −5V is omitted.

  Since the number of encoder pulses output from the encoder 28 is proportional to the amount of rotation of the DC motor 26, the number of encoder pulses (encoder pulse frequency) output from the encoder 28 per second is the amount of rotation of the DC motor 26 per second. It will be proportional to Therefore, in the present embodiment, the encoder pulse frequency (Hz) described above is used as a measure of the rotational speed of the DC motor 26 in place of the generally used number of revolutions per minute (rpm).

  Note that the DC motor 26 rotates forward when the drive voltage is larger than 0V, and reversely rotates when the driving voltage is smaller than 0V. In the following, the DC motor 26 rotates forward. A range in which the drive voltage is greater than 0V will be described.

  As shown in FIG. 4, when the drive voltage is in the range of +5 V or more, the rotational speed of the DC motor 26 increases as the drive voltage increases. However, in the range where the drive voltage is smaller than + 5V, even if the drive voltage increases, the rotation speed is 0 and the DC motor 26 does not rotate. This is because the DC motor 26 cannot obtain a torque that exceeds the static friction force at a drive voltage within a range (dead band) of −5V to + 5V.

  Here, the relationship between the reading resolution in the sub-scanning direction in the scanner device and the rotational speed of the DC motor 26 will be considered. Since the scanner device reads the document while moving the image sensor 20 in the sub-scanning direction, the image sensor 20 must be moved at a speed corresponding to the designated resolution and color mode. For example, when the color mode is the monochrome mode and the resolution in the sub-scanning direction is specified to be read at 4800 dpi, the image sensor 20 is set to a period corresponding to 4800 (lines) per inch × “preferred charge accumulation period”. And you have to move it. In the case of the color mode, since each of R, G, and B needs to be read, if it is specified that the resolution in the sub-scanning direction is 4800 dpi, 4800 (lines) per inch. X “Preferred charge accumulation period” x 3 It must be moved in a period corresponding to 3.

  Here, the “preferred charge accumulation period” is a period (charge accumulation period) in which each light receiving element of the CCD receives light and accumulates charges, for each color of R, G, and B, for one pixel. This is a period preset as an ideal period for outputting a signal. If there is a variation in the charge accumulation period, the color of the read image varies, so that the scanner device always accumulates charges only during this preferred charge accumulation period.

  On the other hand, increasing the reading resolution in the sub-scanning direction increases the number of lines to be read per inch. Therefore, even when the reading resolution in the sub-scanning direction is increased, the speed at which the image sensor 20 is moved must be reduced in order to accumulate charges in the respective light receiving elements for a suitable charge accumulation period.

  For example, when the designated resolution in the sub-scanning direction is 9600 dpi, it is necessary to move the image sensor 20 in a period corresponding to 9600 (lines) per inch × “preferred charge accumulation period”. The moving speed must be half that of 4800 dpi.

  Such a relationship also exists for the resolution in the main scanning direction. The maximum resolution in the main scanning direction is determined by the arrangement density of the CCD light receiving elements in the main scanning direction. For example, when 1200 light receiving elements are arranged per inch, the maximum resolution in the main scanning direction is 1200 dpi. Here, when the resolution in the main scanning direction is changed, the charges output from the plurality of light receiving elements are added. That is, the resolution can be halved by adding the charges from the two light receiving elements arranged in the main scanning direction to one output. For example, in the case of an image sensor having a resolution of 1200 dpi in the main scanning direction, the resolution is 600 dpi by adding outputs from two light receiving elements. When adding charges from a plurality of n light receiving elements in this way, the maximum charge amount that the circuit can tolerate is determined, so that the charge amount after addition does not exceed the maximum charge amount. Therefore, the preferred charge accumulation period needs to be 1 / n. For this reason, when the resolution in the main scanning direction is high, the preferred charge accumulation period becomes longer than when the resolution is low, and therefore the moving speed of the image sensor 20 must be slow.

  When the scan mode is the color mode, the LEDs are turned on in the order of R, G, and B, and the reflected light from the light sources of the respective colors is received by the image sensor 20 and converted into image data. On the other hand, in the monochrome mode, a single color (for example, G) LED is turned on to perform scanning. For this reason, in the color mode, it is necessary to secure a suitable charge accumulation period that is approximately three times that in the monochrome mode, so the speed at which the image sensor 20 is moved must be reduced.

  In order to move the image sensor 20 at a slower speed, the carriage 14 must be transported slower, and for this purpose, the DC motor 26 must be rotated at a slower rotational speed.

  Therefore, when the resolution in the sub-scanning direction and the main scanning direction is made higher or when scanning in the color mode, the DC motor 26 has to be rotated at a slower rotational speed. Such a specific relationship between the scan setting and the rotational speed of the DC motor 26 is obtained in advance by measurement.

  For example, taking the resolution in the sub-scanning direction as an example, as shown in FIG. 4, in the configuration of this embodiment, in order to rotate the DC motor 26 at 2 KHz (encoder pulse frequency, the same applies hereinafter), the drive voltage Is required to be + 5V.

  Here, by setting the drive voltage to a voltage higher than + 5V, the rotational speed of the DC motor 26 becomes faster, and as a result, the resolution in the sub-scanning direction becomes lower. For example, as shown in FIG. 4, by setting the drive voltage to +10 V, the rotational speed of the DC motor 26 becomes 4 KHz.

  On the other hand, in order to make the rotation speed of the DC motor 26 lower than 2 KHz, the drive voltage must be set to a voltage smaller than + 5V. However, as described above, since the DC motor 26 has a dead zone of −5 V to +5 V, the DC motor 26 does not rotate when the drive voltage is made lower than +5 V. Therefore, the DC motor 26 cannot be rotated at a rotational speed of less than 2 KHz.

  Therefore, in the present embodiment, the DC motor 26 is rotated by performing an extremely low speed rotation process, which will be described later, at a rotation speed of less than 2 KHz. On the other hand, when reading a document with a resolution of 2 KHz or higher, the DC motor 26 is rotated by PID (Proportional Integral Differential) control described later. Hereinafter, a state in which these controls are selected according to the setting contents and the DC motor 26 is driven will be described.

  The user places a document on the contact glass 13 shown in FIG. 1 and operates the operation button 16 or operates an input device of a personal computer (not shown) connected via the external I / F 504 to It is assumed that the start of reading is instructed by specifying the resolution, color mode, and reading area in the scanning direction and the sub-scanning direction. Then, the following processing shown in FIG.

  Step S10: The CPU 501 acquires information relating to the resolution in the main scanning direction and the sub-scanning direction input from the operation button 16 or the personal computer. For example, information indicating that the resolution in the main scanning direction is 1200 dpi and the resolution in the sub-scanning direction is 2400 dpi is acquired.

  Instead of directly inputting the resolution, for example, three “clean”, “normal”, and “fast” scanning modes are prepared, and the user selects one of these during scanning. The resolutions in the main scanning direction and the sub scanning direction corresponding to the selected scanning mode may be acquired from the memory 502, for example. According to such a method, it is possible to easily select a resolution according to the purpose of the user.

  Further, the resolution may be set according to the type of document used. For example, a high resolution may be selected for a transparent original (film or the like) or a photograph, and a low resolution may be automatically selected for a plain paper. Alternatively, the resolution may be selected according to the combination of the document type and the scanning mode. For example, when a document type is selected, resolution candidates are narrowed down, and by selecting a scanning mode such as “clean”, “normal”, and “fast” from the narrowed candidates, for example. A specific resolution may be determined. The above-described case is the case of the main scan for reading the image data. However, in the case of the pre-scan, it is sufficient to acquire rough information about the image. In this case, the CPU 501 has a low resolution. Is automatically selected.

  Here, the “setting contents related to scanning” described in claim 1 may be contents set by the user, or contents automatically set by the printing apparatus 10 (for example, as described above) Pre-scan resolution).

  Step S11: The CPU 501 acquires information regarding the color mode input from the operation button 16 or the personal computer. For example, the CPU 501 acquires information indicating that the color mode is the color mode.

  Step S12: The CPU 501 refers to the table stored in the memory 502, and determines which of the extremely low speed rotation control and the PID control is selected. Specifically, the memory 502 stores a table as shown in FIG. The upper part of FIG. 6 shows the relationship between the main scanning resolution and sub-scanning resolution and the contents of control when the color mode is set to the color mode. Further, the lower part shows the relationship between the main scanning resolution and sub-scanning resolution and the control content when the color mode is set to the monochrome mode. In this example, the color mode table rotates at a very low speed when the main scanning resolution is 1200 dpi and the sub-scanning resolution is 600 dpi to 2400 dpi, and when the main scanning resolution is 600 dpi and the sub-scanning resolution is 1200 dpi. Control is selected. Also, when the main scanning resolution is 300 dpi and the sub-scanning resolution is 75 dpi to 600 dpi, the main scanning resolution is 600 dpi and the sub-scanning resolution is 300 dpi and 600 dpi, and the main scanning resolution is 1200 dpi and the sub-scanning is performed. PID control is selected when the resolution is 150 dpi. In other cases, the combination of resolutions is “−” because it cannot be selected. On the other hand, in the case of the table for the monochrome mode, when the main scanning resolution is 1200 dpi and the sub-scanning resolution is 600 dpi, the ultra-low speed control is changed to the PID control as compared with the color mode table. Other than that, it is the same as for the color mode.

  The table shown in FIG. 6 is an example, and it goes without saying that a table other than these may be used.

  Step S13: The DC motor control unit 513 moves the carriage 14 to the reading start position in accordance with the designated document size. The movement of the carriage 14 is omitted for convenience of explanation.

  Step S14: The CPU 501 determines whether or not an instruction to start scanning has been received from, for example, the operation button 16 or a personal computer (not shown). If received, the process proceeds to step S15. Repeat the process.

  Step S15: The CPU 501 rotates the DC motor 26 by one line and executes a process for scanning the image sensor 20 by one line. Specifically, the CPU 501 supplies a command to the DC motor control unit 513 and moves the carriage 14 by one line by extremely low speed rotation control described later. Further, the CPU 501 supplies a control signal to the image sensor control unit 511, turns on the R, G, and B LEDs, and executes a process of converting the reflected light into image data and reading it. As a result, the original is scanned for one line, and corresponding image data is generated and output. Control regarding the image sensor 20 will be described later with reference to FIG. 8, and control of the DC motor 26 will be described later with reference to FIG.

  Step S16: The CPU 501 determines whether both rotation corresponding to one line of the DC motor 26 (movement of the carriage 14) and scanning for one line by the image sensor 20 have been completed, and both have ended. If so, the process proceeds to step S17. Otherwise, the same process is repeated. As will be described later, since the time required for rotation for one line is set to be shorter than the time required for scanning for one line, normally, after the rotation for one line is completed. After a predetermined time has elapsed, the scanning is completed, and it is determined that the rotation and scanning for one line have been completed, and the processing for the next line is started. However, since it may be assumed that the time required for rotation exceeds the time required for scanning due to some factor, in order to perform normal operation even in such a case, in the process of step S16, the scanning and rotation are performed. It waits for both to finish and proceeds to the next line.

  Step S17: The CPU 501 determines whether or not scanning of all the lines constituting the area to be scanned has been completed. If completed, the process proceeds to step S19. Otherwise, the process returns to step S15. Similar processing is repeated.

  Step S18: The DC motor control unit 513 rotates the DC motor 26 at a constant speed based on PID control, executes scanning by the image sensor 20, reads all lines in the scanning region, and converts them into image data.

  FIG. 8 shows functional blocks formed in the DC motor control unit 513 when PID control is executed. In this figure, the subtraction circuit 521 calculates a deviation between the target speed (target moving speed) of the carriage 14 supplied from the CPU 501 and the speed information generated based on the encoder pulse output from the encoder 28. This is supplied to the adder circuit 523. The subtraction circuit 522 calculates a deviation between the target position of the carriage 14 supplied from the CPU 501 and position information generated based on the encoder pulse output from the encoder 28, and supplies the deviation to the addition circuit 523. A constant multiplier circuit that outputs the subtracters 521 and 522 by multiplying the outputs by a predetermined number may be provided.

  The addition circuit 523 adds the signals output from the subtraction circuits 521 and 522 and outputs the result. The proportional element (P) 524 multiplies the output of the adder circuit 523 by a constant and outputs the result. The integral element (I) 525 integrates and outputs the output of the adder circuit 523. The differential element (D) 526 differentiates the output of the adder circuit 523 and outputs the result. The adder circuit 527 adds the outputs of the proportional element 524, the integral element 525, and the derivative element 526, and supplies the sum to the drive circuit 528. The drive circuit 528 controls the DC motor 26 by PWM control according to the output of the adder circuit 527. In the PID control, the control is performed by the voltage outside the dead band of the DC motor 26, and therefore the DC motor 26 is continuously driven.

  Step S19: The CPU 501 stores the image data obtained by scanning in the image data storage unit 502a of the memory 502. When the capacity of the image data exceeds the capacity of the image data storage unit 502a, for example, the image data is transferred to the memory card M via the memory I / F 503 and stored therein, or the image data is stored via the external I / F. You may make it memorize | store in the memory | storage device of the personal computer which is not shown in figure. According to such a configuration, the image data can be reliably stored even when the resolution is set high.

  Next, the details of the “scanning process” in the “rotation / scanning process” shown in step S15 of FIG. 5 will be described with reference to FIG. Note that the rotation process of the rotation / scanning process and the scanning process are executed in parallel, but the rotation process will be described below after the description of the scanning process. When the processing of the flowchart of this figure is started, the following steps are executed.

  Step S30: The CPU 501 refers to the output of the encoder control unit 512, determines whether or not an encoder pulse has been detected, proceeds to step S31 if it is detected, and repeats similar processing otherwise.

  Step S31: The image sensor control unit 511 supplies drive pulses to the image sensor 20, and instructs reading of the document. Specifically, the image sensor control unit 511 sets the image sensor driving pulse shown in FIG. 9 to a high state. Thereby, the image sensor 20 performs the operation | movement mentioned later.

  In FIG. 9, the upper row shows the timing when each of the R, G, and B LEDs is lit (lights on high, lights off when low). The next stage shows an image sensor driving pulse input to the image sensor 20. The next stage shows two-phase encoder pulses output from the encoder 28. The lower row shows the drive voltage applied to the DC motor 26 by the DC motor control unit 513. The encoder pulse has two encoder pulses (a) and (b) that are shifted by π / 2.

  Step S32: The image sensor 20 transfers the charge accumulated by turning on the B (blue) LED in the previous period to the image sensor control unit 511 and outputs it. Thereby, image data for one line corresponding to B is obtained.

  Step S33: The image sensor control unit 511 turns on an R (red) LED provided on the carriage 14 (see FIG. 9). As a result, the light emitted from the R LED is applied to the document. The reflected light reflected by the document is received by the light receiving elements arranged in a line of the image sensor 20, and charges corresponding to the intensity of the reflected light are accumulated in the light receiving elements.

  Step S34: The image sensor control unit 511 refers to the built-in timer 511a to determine whether or not a suitable accumulation time has elapsed. If it has elapsed, the process proceeds to step S35, and otherwise Repeat the process. The preferred charge accumulation time is set in advance as an ideal period for outputting a signal for one pixel in a period (charge accumulation period) in which each light receiving element of the CCD receives light and accumulates charge. It is a period.

  Step S35: The image sensor control unit 511 turns off the R LED (see FIG. 9). As a result, each light receiving element receives the light irradiated from the R LEDs and reflected from the original for a time corresponding to the preferred accumulation time, and accumulates the charges.

  Step S <b> 36: The image sensor control unit 511 outputs a drive pulse to the image sensor 20. Specifically, the image sensor control unit 511 sets the image sensor driving pulse shown in FIG. 9 to a high state.

  Step S37: In the period from Step S33 to Step S35, the image sensor 20 transfers the electric charge accumulated by turning on the R LED to the image sensor control unit 511 and outputs it. Thereby, image data for one line corresponding to R is obtained.

  Step S38: The image sensor control unit 511 turns on the G (green) LED provided in the carriage 14. As a result, the light emitted from the G LED is irradiated and reflected on the original, and is received by the light receiving elements arranged in a line shape of the image sensor 20, and charges corresponding to the intensity of the reflected light are accumulated.

  Step S39: The image sensor control unit 511 refers to the built-in timer 511a to determine whether or not a suitable accumulation time has elapsed. If it has elapsed, the process proceeds to step S40, otherwise the same. Repeat the process.

  Step S40: The image sensor control unit 511 turns off the G LED. As a result, each light receiving element receives the light irradiated from the G LED and reflected by the document for a time corresponding to a suitable accumulation time, and accumulates electric charges.

  Step S41: The image sensor control unit 511 outputs a drive pulse to the image sensor 20. Specifically, the image sensor control unit 511 sets the image sensor driving pulse shown in FIG. 9 to a high state.

  Step S42: In the period from Step S38 to Step 40, the image sensor 20 transfers the electric charge accumulated by turning on the G LED to the image sensor control unit 511 and outputs it. Thereby, image data for one line corresponding to G is obtained.

  Step S43: The image sensor control unit 511 turns on the B (blue) LED provided in the carriage 14. As a result, the light emitted from the blue LED is irradiated onto the original and reflected, and is received by the light receiving elements arranged in a line of the image sensor 20, and charges corresponding to the intensity of the reflected light are accumulated.

  Step S44: The image sensor control unit 511 refers to the built-in timer 511a to determine whether or not a suitable accumulation time has elapsed. If it has elapsed, the process proceeds to step S45, otherwise the same. Repeat the process.

  Step S45: The image sensor control unit 511 turns off the B LED. As a result, each light receiving element receives the light emitted from the B LED and reflected from the document for a time corresponding to a suitable accumulation time, and accumulates electric charges. The electric charge accumulated by the B LED is transferred in the next step S32.

  Next, the “rotation process” in the “rotation / scanning process” shown in step S15 of FIG. 5 will be described with reference to FIG. Note that the rotation process shown in FIG. 10 corresponds to the extremely low speed rotation process described above. When the processing of the flowchart of this figure is started, the following steps are executed.

  Step S60: The DC motor control unit 513 reads the duty ratio increase rate from a register (not shown). The duty ratio increase rate indicates the degree of increase of the duty ratio with the passage of time, and the DC motor control unit 513 gradually increases the duty ratio at the duty ratio increase rate while measuring with a timer (not shown).

  Step S61: The DC motor control unit 513 determines whether or not the edge of the encoder pulse has been detected, and increases the duty ratio until it is determined that the edge has been detected.

When the duty ratio is gradually increased at the duty ratio increase rate in this way, the drive voltage gradually increases as shown in FIG. When the drive voltage goes out of the dead band (−5 V to ++ 5 V) range, the stopped DC motor 26 starts rotating. As a result, if the encoder pulse (a) is at a high level at the time when the extremely low speed rotation process is started, the encoder pulse (a) changes from a high level to a low level. When the encoder pulse (a) changes from the high level to the low level, the DC motor control unit 513 determines that an edge has been detected, and proceeds to step S62.

  Step S62: The DC motor control unit 513 reads out the number of end pulses from the register, and the number of encode pulses (a) and (b) detected after starting the extremely low speed rotation process reaches the number of end pulses. Determine whether or not. If the end pulse number has been reached, the process proceeds to step S64, and otherwise, the process proceeds to step S63.

  Step S63: The DC motor control unit 513 reads the dead band duty ratio from the register, decreases the duty ratio to this dead band duty ratio, returns to step S60, and repeats the same processing as described above.

  Here, the dead band duty ratio is a duty ratio corresponding to a drive voltage within the range of the dead band. It is assumed that the duty ratio corresponding to the drive voltage +2.5 V is stored in the register as the dead band duty ratio corresponding to the resolution in the selected sub-scanning direction. When the duty ratio is increased in the second processing of step S60, the drive voltage gradually increases from + 2.5V. When the dead band is removed and becomes + 5V or more, the DC motor 26 starts rotating again. Then, as shown in FIG. 9, the encoder pulse (b)) is now changed from the high level to the low level.

  Therefore, the DC motor control unit 513 detects the edge of the encoder pulse (b). Even when this edge is detected, since the new encoder pulses (a) and (b) are not detected after starting the very low speed rotation process, the DC motor control unit 513 performs the process of step S63 again, Reduce the duty ratio to the deadband duty ratio.

  As described above, when the processes of steps S60 to S63 are repeatedly executed, the DC motor 26 repeats rotation and stop, and the DC motor control unit 513 generates new encoder pulses (a) and (b). Come to detect. If it is determined in step S62 that the detected pulse number has reached the end pulse number, the DC motor control unit 513 proceeds to step S64.

  Step S64: The DC motor control unit 513 sets the duty ratio to 0 and stops the rotation of the DC motor 26.

  As a result of the extremely low speed rotation processing described above, as shown in FIG. 9, the DC motor control unit 513 performs an encoder pulse ( For example, 10 pieces of a) and (b) are input.

  Here, the duty ratio increase rate used in step S202 is obtained in advance by measurement as an increase rate such that the period required to rotate the DC motor 26 by 10 encoder pulses by the extremely low speed rotation process is 9 ms. Stored in the register. Therefore, as shown in FIG. 9, there is a waiting period of 1 ms from the end of the extremely low speed rotation period until the next image sensor drive pulse is input and the very low speed rotation process is started again. Since the DC motor 26 is stopped during this waiting period, the DC motor control unit 513 inputs 10 encoder pulses within a total of 10 ms of the extremely low speed rotation period and the waiting period.

  The DC motor control unit 513 performs the above-described extremely low speed rotation process every time an image sensor drive pulse is input from the image sensor control unit 511. Therefore, the encoder pulse 10 is input every 10 ms of the input interval of the image sensor drive pulse. The DC motor 26 can be rotated by the number of pieces. As a result, the image sensor 20 can read the document with a predetermined resolution.

  Note that the above-described waiting time is before the next image sensor driving pulse is input even if the extremely low speed rotation period is slightly longer than a predetermined length (9 ms) due to uneven rotation of the DC motor 26 or the like. In addition, this is a preliminary period provided so that the extremely low speed rotation period ends.

  As described above, according to the embodiment of the present invention, the control method of the DC motor 26 is selected from the PID control and the extremely low speed rotation mode according to the resolution and the color mode. The DC motor 26 can be controlled by an optimal control method. As a result, the DC motor 26 can be used in a wide range of speeds, so that the DC motor 26 can be used instead of a stepping motor that has a wide range of usable speeds but a large operating noise.

  The above embodiment is merely an example, and there are various other modified embodiments. For example, in the above embodiment, the DC motor 26 is controlled by changing the applied voltage as shown in FIG. 9, but the DC motor 26 may be controlled by changing the current. Good.

  In the above embodiment, the ultra-low speed control or the PID control is selected according to the resolution and the color mode. However, for example, the control may be selected with reference to only the resolution.

  Further, in the above embodiment, when the extremely low speed rotation control is selected, only the very low speed rotation control is adopted in all the sections. However, for example, PID control and extremely low speed are performed in one scan. You may make it combine rotation control. For example, when the time required for one scan is 10 ms and the rotation is performed by 10 encoder pulses, the first 1 ms (initial rotation period) is driven by 9 encoder pulses by PID control, and the latter 9 ms (very low speed). The rotation period) may be driven by one encoder pulse by extremely low speed rotation control. Note that the period may be shorter or longer than 1 ms. In order to make the initial rotation period shorter than 1 ms, the number of initial pulses may be set to another value of 8 or less such as 8 or 7 instead of “9” described above. Alternatively, instead of the duty ratio corresponding to +22.5 V in the embodiment, the initial duty ratio is set to a duty ratio corresponding to a larger voltage, so that the DC motor 26 is equivalent to nine encoder pulses in a shorter time. What is necessary is just to make it rotate.

  On the other hand, in order to make the driving time by the PID control longer than 1 ms, the initial duty ratio is changed to the duty ratio corresponding to a smaller voltage instead of the duty ratio corresponding to +22.5 V in the embodiment, so that the DC The motor 26 may be rotated by nine encoder pulses in a longer time.

  As described above, when the initial rotation period is shortened, the extremely low speed rotation period may be lengthened accordingly. Therefore, a value smaller than the value in the above-described case may be stored in the register as the duty ratio increase rate, and the speed at which the drive voltage increases may be made slower. Alternatively, the dead zone duty ratio may be made smaller than the value in the above-described case so that the period until the temporarily stopped motor starts rotating again may be lengthened. In addition, what is necessary is just to reverse to the case where it shortened when the initial period of rotation is lengthened.

  In the above embodiment, the dead band duty ratio is a duty ratio corresponding to the drive voltage +2.5 V. However, the present invention is not limited to this, and the voltage is within the range of the dead band. Any corresponding duty ratio may be used. For example, a duty ratio corresponding to + 1V, a duty ratio corresponding to + 4V, or the like may be used.

  Even in this case, since the drive voltage (or drive current) is within the dead zone, the rotation of the DC motor 26 can be temporarily stopped. Even when the dead band duty ratio is changed, the duty ratio increase rate may be changed in order to set the extremely low speed rotation period to 8 ms or 9 ms as in the above embodiment. That is, as a duty ratio increase rate corresponding to the dead band duty ratio, a value that makes the extremely low speed rotation period 8 ms or 9 ms is obtained in advance by measurement and stored in the register.

  In the above embodiment, every time an encoder pulse edge is detected, the duty ratio is increased or the duty ratio is decreased to the dead band duty ratio. However, only a predetermined number of edges of 2 or more are detected. The duty ratio may be increased or decreased each time.

  Further, in the above embodiment, a waiting period of 1 ms is provided. However, the predetermined charge accumulation period may be set to an extremely low speed rotation period without providing this waiting period.

  In the above embodiment, the DC motor 26 to be controlled in the extremely low speed rotation processing is the carriage motor for the carriage 14 provided in the scanner device, but the present invention is not limited to this. As for the motors provided in other devices, by performing the above-mentioned extremely low speed rotation process, the motor is driven at a slower average rotation speed than when the motor is continuously rotated by applying a voltage outside the dead band as the drive voltage. Can be rotated.

  In the above embodiment, the operation in the color mode has been described as an example. However, in the monochrome mode, one of the R, G, and B LEDs is lit and accumulated in the image sensor 20. Charges are output as image data. Specifically, in FIG. 9, for example, only the R LED is lit, and G and B are not lit. Then, the electric charge accumulated by turning on the R LED is transferred at the next R lighting. Note that instead of R, only G may be lit.

  In the above embodiment, R, G, B LEDs are sequentially turned on to generate R, G, B image data. For example, a white cold cathode tube or LED is turned on, Image data may be generated by an image sensor for three lines having R, G, and B filters.

  In the above embodiment, the DC motor 26 to be controlled is a motor that operates with DC power, but an AC motor may be used instead of the DC motor. In this case, the frequency of the drive voltage (alternating current) applied to the AC motor is gradually increased, and the AC motor is rotated so that the dead zone is removed from the dead zone within the AC motor frequency. If the edge of the encoder pulse is detected, the drive voltage frequency may be lowered and adjusted so as to fall within the dead band range.

  In the above embodiment, the image sensor 20 is a CIS type image sensor, but may be an optical reduction type image sensor instead of the CIS type. Even in the optical reduction method, the scanner includes a motor for moving the carriage on which the light source and the mirror are mounted. Therefore, the motor can be rotated at an extremely low speed by executing the extremely low speed rotation process described above. As a result, since this carriage can be transported at a very low speed, an image having a higher resolution than that obtained when a voltage outside the range of the dead zone is applied as the drive voltage and the motor is continuously rotated is obtained. be able to.

  In the above embodiment, the DC motor control unit 513 adjusts the drive voltage using the PWM control method. However, instead of the PWM control method, the DC motor control unit 513 uses the PAM (Pulse Amplitude Modulation) control method. You may make it do. Further, the adjustment may be performed by a control method combining these PWM control method and PAM control method.

  In the above embodiments, the encoder is a rotary encoder. However, instead of the rotary encoder, another encoder such as an encoder provided with a Hall element or a resolver may be used.

  In the above embodiment, a part of the configuration realized by hardware may be replaced with software. For example, the application voltage control (PWM control) performed by the motor drive control unit (ASIC) may be realized by software.

It is a figure which shows the structural example of the printing apparatus which concerns on embodiment of this invention. FIG. 2 is a diagram illustrating a configuration example of a scanner of the printing apparatus illustrated in FIG. 1. 3 is a detailed configuration example of a control circuit shown in FIG. It is a figure which shows the relationship between the applied voltage of a DC motor, and a rotational speed. 3 is a flowchart executed in the printing apparatus shown in FIG. 1. It is a figure which shows the relationship between the resolution and the kind of control. It is a block diagram for implement | achieving PID control. It is a flowchart which shows an example of the scanning process shown in FIG. It is a figure which shows the drive signal etc. of LED. It is a flowchart which shows an example of the rotation process shown in FIG.

Explanation of symbols

  14 Carriage, 20 Image sensor, 26 DC motor (moving means), 501 CPU (selecting means), 513 DC motor control section (first control means, second control means)

Claims (7)

A scanner device that scans a predetermined scan object and generates image data,
An image sensor for converting the optical image of the scan object into corresponding image data;
Moving means for moving the carriage having the image sensor in the sub-scanning direction;
First control means for controlling the moving means by a first control process;
Second control means for controlling the moving means by a second control process different from the first control process;
Selection means for selecting the first or second control means in accordance with the setting content relating to scanning;
A scanner device comprising:   The scanner device according to claim 1, wherein the moving unit includes a DC motor for moving the carriage in a sub-scanning direction. The first control means performs control according to the position of the carriage,
The second control means performs control according to the position and speed of the carriage,
The selection means selects the first control means when moving the motor of the movement means at a predetermined speed or less, and selects the second control means in other cases.
The scanner apparatus according to claim 1 or 2, wherein The first control means is driven so that the motor of the moving means rotates intermittently,
The second control means drives the motor included in the moving means to rotate continuously,
The selection means selects the first control means when moving the motor of the movement means at a predetermined speed or less, and selects the second control means in other cases.
The scanner apparatus according to claim 1 or 2, wherein   3. The scanner device according to claim 1, wherein the selection unit selects the first and second control units according to resolution or monochrome / color of image data to be obtained.   A printing apparatus comprising the scanner device according to claim 1. A scanning method for generating image data by scanning a predetermined scanning object,
A carriage having an image sensor that selects a first control process and a second control process different from the first control process in accordance with the setting content relating to scanning, and converts the optical image of the scan object into corresponding image data. Do control to move,
A scanning method characterized by the above.

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