JP2012019269A - Image read apparatus and image read control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image read apparatus and an image read control method which reduce time necessary to complete manuscript reading regardless of a stopping position of a carriage.SOLUTION: The image read apparatus comprises a carriage provided with a line sensor extending in a main scanning direction and the carriage moves in a sub-scanning direction for scanning a manuscript to read an image on a manuscript by the line sensor. An HP sensor 108 and a flag 107 detect whether the scanning carriage is positioned at HP. The position of the carriage in the sub-scanning direction is detected as a carriage position depending on a mark 109. The image read apparatus executes an initialization control when it is detected that the carriage is positioned at HP before an image reading operation. When it is not detected that the carriage is positioned at HP, and a distance between the carriage position and HP is farther than a predetermined distance, the image read apparatus transfers the carriage in a direction toward HP by raising a travel speed of the carriage in comparison with a case where a distance between the carriage position and HP is equal to or below the predetermined distance.

Description

  The present invention relates to an image reading apparatus, an image reading apparatus, and an image reading control method for reading an image on an original, and in particular, shortens an initialization operation and reduces a driving sound to drive a carriage (original scanning means). The present invention relates to an image reading apparatus and an image reading control method for controlling.

  Generally, in an image reading apparatus, when reading an image on a document, the image is read by scanning the document with a carriage (document scanning means). When scanning a document, an HP sensor (home position sensor) serving as a scanning position reference is detected, and the carriage position is initialized. That is, the carriage position is adjusted to the scanning reference position.

  However, if the carriage is not stopped near the HP sensor when the image reading apparatus is turned on, it is necessary to move the carriage to the scanning reference position and wait until the HP sensor detects the carriage. For this reason, it takes time until reading of the document is started, and as a result, it takes time to read the document. Further, in the conventional image reading apparatus, when the carriage drive control is started and the HP sensor is not detected within a predetermined time, it is determined that the drive control system is defective, and the control is stopped. Thereafter, failure notification is sent to the operator via an operation panel provided in the image reading apparatus.

  Note that the carriage may move when the image reading apparatus is moved. In such a case, it may stop at a position away from the carriage HP sensor. Further, when the operation of the image reading apparatus is stopped due to a power failure during document scanning, it may stop at a position away from the carriage HP sensor. Further, when the image reading apparatus is stopped due to malfunction detection, the image reading apparatus may stop at a position away from the carriage HP sensor.

  As described above, if it takes a document reading time (scanning time) after the power is turned on, it is inconvenient for the user. For this reason, in order to shorten the reading time, a predetermined range from the scanning reference position (scanning start position) of the carriage to the position just before the document setting position is controlled by, for example, the high-speed driving of the carriage by the two-layer excitation method. (For example, refer to Patent Document 1). Here, from the position before the document setting position to the rear end of the document area, the carriage drive is controlled by the 1-2 phase excitation method. That is, variable scanning speed control is performed.

  On the other hand, in some image reading apparatuses, position detection markings are provided within a reading area of a CCD (Charge Coupled Device) and outside a document range (see, for example, Patent Document 2). Here, when the power is turned on during the initial alignment of the carriage, the position detection marking is read to determine the position of the carriage. As a result, when the power is turned on, if the carriage is at the home position, the positioning operation for initial alignment is omitted to shorten the initialization operation time.

JP-A-5-37740 Japanese Patent Laid-Open No. 2003-324583

  As described above, in the image reading apparatus, it is detected by the HP sensor whether or not the carriage is at HP (home position: reference position). On the other hand, in the image reading apparatus, there are inevitable machine differences due to so-called mechanical accuracy and assembly tolerances. And the error resulting from such a machine body difference etc. is correct | amended with the detection output from a HP sensor. That is, in the image reading apparatus, there is a variation in carriage drive control for each machine body due to a pulley, a driven pulley, a timing belt, and the like used in the drive system and mechanical manufacturing tolerances. This variation is corrected by the detection output from the HP sensor. Therefore, in the image reading apparatus, it is necessary to always perform HP detection when performing calibration of the scanning position before starting scanning of the document.

  Normally, when original scanning is performed, the carriage is driven and controlled in the same way as the forward path after reading the original. When the HP sensor detects that the carriage has returned to HP, the carriage stops. As described above, when the document reading apparatus is in the energized state, the carriage position information is updated and held based on the detection output of the HP sensor. Since the drive control unit for driving the carriage is excited, the carriage is held on the HP without moving.

  However, in the image reading apparatus, when the power is off, the drive control unit is not excited, and therefore, if an external force is applied to the carriage, the carriage easily moves. Therefore, even if the carriage is moved from the HP after the previous image reading, even if the carriage has been stored, even if the carriage position is stored, It is necessary to detect the position again.

  Similarly, if the safety device operates due to some trouble during document scanning or if a power failure occurs, the carriage may be stopped at a position away from the HP.

  Thus, when the power is turned on, it is necessary to detect whether or not the carriage is positioned at the HP, and the time required for this HP detection becomes longer than the time required for the document reading operation. In other words, unless the stop position of the carriage is known, optimal drive control of the carriage cannot be performed. For this reason, when the stop position of the carriage is not known, it is necessary to perform HP detection by low-speed driving so as not to cause a problem due to carriage movement control. This is because if the HP detection is performed at high speed control, the carriage stop position accuracy deteriorates. Furthermore, it is necessary to prevent the positional deviation and the like from occurring due to the vibration of the carriage affecting the document.

  As described above, in the conventional image reading apparatus, the time required for HP detection varies greatly depending on the stop position of the carriage before the start of document scanning. As a result, the time required to complete the document reading may become abnormally long.

  Accordingly, an object of the present invention is to provide an image reading apparatus and an image reading control method capable of shortening the time required to complete document reading regardless of the carriage stop position.

  In order to achieve the above object, an image reading apparatus according to the present invention includes an image reading unit extending in a predetermined first direction, and moves in a second direction orthogonal to the predetermined direction to move an object to be scanned. Reference position detection for detecting whether or not the scanning carriage is positioned at a predetermined reference position in an image reading apparatus having a scanning carriage that scans and reads an image on the object to be scanned by the image reading unit Means, a carriage position detecting means for detecting the position of the scanning carriage in the second direction as a carriage position, and the scanning carriage is positioned at the reference position by the reference position detecting means prior to the image reading operation. If it is detected, the initialization control means for executing predetermined initialization control, and prior to the image reading operation, If it is not detected by the reference position detection means that the scanning carriage is positioned at the reference position, the carriage position and the reference position are determined when the distance between the carriage position and the reference position is greater than a predetermined distance. And a movement control means for moving the scanning carriage in the direction of the reference position at a higher moving speed of the scanning carriage than when the distance to the position is equal to or less than the predetermined distance.

  According to the present invention, if it is not detected that the scanning carriage is positioned at the reference position, if the distance between the carriage position and the reference position is greater than a predetermined distance, the distance between the carriage position and the reference position is The scanning carriage is moved in the direction of the reference position by setting the moving speed of the scanning carriage to be higher than that when the distance is equal to or less than the predetermined distance. Therefore, the initialization control can be performed by quickly moving the scanning carriage to the reference position in accordance with the stop position of the carriage, and as a result, the time required to complete reading of the document that is the object to be scanned is shortened. Can do.

1 is a diagram schematically illustrating a configuration of an example of an image reading apparatus according to an embodiment of the present invention. It is a block diagram for demonstrating the hardware constitutions of the image reading apparatus shown in FIG. FIG. 2 is a perspective view showing a structure (configuration) of the carriage shown in FIG. 1, (a) is a diagram showing an overall configuration of the carriage, and (b) is a diagram showing a configuration of a part of the carriage. FIG. 2 is a diagram for explaining carriage position detection in the image reading apparatus shown in FIG. 1. FIG. 5 is a diagram for explaining carriage position detection using the indicator plate shown in FIG. 4. It is a figure for demonstrating the drive control of the carriage shown in FIG. It is a figure for demonstrating the document illumination part shown in FIG. It is a figure which shows the structure of an example of the lighting control circuit for carrying out lighting control of the original document illumination part shown in FIG. FIG. 5 is a diagram for explaining an example of a layout of a carriage position detection mark shown in FIG. 4. 5 is a flowchart for explaining an example of the operation of the image reading apparatus shown in FIG. 4. 5 is a flowchart for explaining an example of the operation of the image reading apparatus shown in FIG. 4. FIG. 5 is a diagram for explaining another example of the layout of the carriage position detection mark shown in FIG. 4, and (a) is a diagram showing an example of a state in which a plurality of density marks are arranged on the scanning surface side of the document index plate; FIG. 7B is a diagram showing another example of a state in which a plurality of density marks are arranged on the scanning surface side of the document index plate.

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

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

  Referring to FIG. 1, the illustrated image reading apparatus 101 includes a line sensor (not shown in FIG. 1) that is a photoelectric conversion unit. The image reading apparatus 101 includes a platen glass (original platen glass) 102 and a flow reading glass 103. A document such as a book is set on the platen glass 102, and reflected light from the document passes through the platen glass 102 and is guided to the line sensor 219. On the other hand, the sheet original conveyed to the image reading apparatus 101 by the original conveying apparatus (not shown) is reflected by the flow reading glass 103 and guided to the line sensor 219.

  In the illustrated example, the platen glass 102 and the flow-reading glass 103 are provided. However, depending on the model, the platen glass 102 and the flow-reading glass 103 may be configured by one glass. Further, in the image reading apparatus 101 called a pressure plate model, since the document conveying apparatus is not mounted, the flow reading glass 103 is removed, and a portion other than the flow reading glass 103 is covered with a blind cover (not shown) or the like. Often covered. In the following description, the document conveying apparatus will not be described.

  The image reading apparatus 101 has a document scanning carriage (hereinafter simply referred to as a carriage) 106. The carriage 106 includes a sensor substrate 111 on which a line sensor is mounted, a document illumination unit (not shown in FIG. 1), and an optical unit (not shown in FIG. 1) such as a lens.

  In the illustrated image reading apparatus 101, when the original 104 is copied, the original 104 is set on the platen glass 102 using the original index plate 109 as a guide. Thereafter, when an operator presses a copy button on an operation panel (not shown), a document reading sequence is started.

  When the document reading sequence is started, the image reading apparatus 101 first performs initialization control (initialization control). As for the initialization control, for example, the operation state of the line sensor, the brightness of the original illumination unit, and the reading state of the reference white plate 105 are performed.

  Therefore, the image reading apparatus 101 detects the flag 107 set on the carriage 106 with the HP sensor 108 and positions the carriage 106. Then, the image reading apparatus drives the carriage in an area (document scanning area) from the reference position (HP) to the white plate 105.

  The carriage 106 does not have a function for detecting the position. For this reason, when the power is turned on, it is not known where in the document scanning area the carriage 106 is stopped. Therefore, when the power is turned on, the reference position is detected by moving the carriage 106 by the low-speed drive control.

  The carriage 106 is driven by a motor (hereinafter referred to as an optical motor) 112. A drive pulley 113 is press-fitted into the drive shaft of the optical motor 112. On the other hand, a drive shaft 117A and a driven shaft 117B extending in a direction crossing the moving direction of the carriage 106 are arranged in the casing of the image reading apparatus 101 with a predetermined interval. And the thread winding parts 121A and 121B are provided in the edge part of this drive shaft 117A, respectively.

  Similarly, thread winding portions 121C and 121D are provided at the ends of the driven shaft 117B, respectively. A driven pulley 116 is attached to the drive shaft 117A adjacent to the thread winding portion 121, and the driven pulley 116 is connected to the drive pulley 113 by a timing belt 115. A wire 119 is passed between the bobbin winding portions 121A and 121C, and a wire 120 is passed between the bobbin winding portions 121B and 121D. The amount of movement of the carriage 106 is defined according to the pulley ratio of the driving pulley 113 and the driven pulley 116, the diameters of the thread winding portions 121A to 121D, and the diameters of the wires 119 and 120.

  Note that a pair of rails 118 are arranged in the casing of the image reading apparatus 101 along the moving direction of the carriage 106. The carriage 106 is connected to the wire 120 and moves on the rail as the wire 119 moves.

  Here, a two-phase stepping motor is used as the optical motor 112, the number of teeth of the driving pulley 113, the number of teeth of the driven pulley 116, the diameters of the thread winding portions 121A to 121D are 30.0 mm, and the wires 119 and 120, respectively. The diameter is 0.80 mm. In this case, the amount of movement of the carriage 106 is shown in Table 1.

  In Table 1, the number of divisions is the number of pulses required when the two-phase stepping motor is controlled to rotate once. The movement angle per pulse is 1.8 degrees. The movement amount of the carriage 106 indicates the movement amount when the FULL-STEP control is performed on the two-phase stepping motor. In the case of a two-phase stepping motor, due to the motor structure, the rotation angle per control pulse is 1.8 °, and the drive control for performing rotation control with 1.8 ° as a basic step angle is a full step ( FULL-STEP).

  If it is driven by W1-2 phase excitation using a dedicated motor driver IC, the amount of movement is controlled by 4 divisions and becomes 0.0448 (mm / step). In addition, when driven by 2W1-2 phase excitation, the movement amount is controlled by 8 divisions and can be controlled at a step size of 0.0224 (mm / step).

  Here, the W1-2 phase excitation and the 2W1-2 phase excitation are more than the basic step angle of 1.8 ° by controlling the current value flowing in the motor coils of the A phase and the B phase in the two-phase stepping motor. This is a method of controlling rotation at a fine angle. In the W1-2 phase excitation and the 2W1-2 phase excitation, rotation control is performed in units of 0.45 ° corresponding to four divisions of FULL-STEP and 0.225 ° corresponding to eight divisions of FULL-STEP, respectively.

  That is, in FULL-STEP and 1 pulse, the optical motor 112 rotates 1.8 ° and the pulley ratio of the driving pulley 112 is 3.0, so that the driven pulley 115 further rotates by 1/3, that is, 0.6. Rotate. In short, a spool of diameter (30.0 + 0.8) mm rotates 0.6 / 360 times. Therefore, the movement amount of the carriage 106 is 30.8 × π × 0.6 ÷ 360≈0.1613 mm.

  A dynamic damper 114 is set on the rear end of the optical motor 112. Then, the dynamic damper 114 suppresses rotation spots and vibrations of the optical motor 112. The dynamic damper 114 is not necessarily required, and is set as necessary.

  By the drive mechanism described above, the carriage 106 moves to a basic position (hereinafter also referred to as a predetermined position) during initialization control. When detecting the position of the carriage 106, the HP sensor 108 is used. A flag 107 extending in a direction crossing the moving direction is attached to the carriage 106, and the flag 107 is detected by the HP sensor 108 when the flag 107 passes through the HP sensor 108. Thus, as will be described later, the relative position of the carriage 106 representing the relationship with the predetermined position is determined, and the position of the document scanning position (main scanning reading line) 122 is known.

  Now, it is assumed that the flag 107 moves from the position shown in FIG. 1 in the direction passing the HP sensor 108, that is, the direction indicated by the solid arrow. At this time, the position at which the flag 107 has passed through the HP sensor 108 (also referred to as the cut position) is normally set to the image destination position (scanning start position) of the document 104 set on the platen glass 102. That is, the document scanning position (main scanning reading line) 122 coincides with one end portion of the document 104. Since the distance from the position of the platen glass 102 to the reference white plate 105 is clear in design, the carriage 106 is equivalent to the number of pulses obtained from the moving distance per pulse from the position where the flag 107 cuts off the HP sensor 108. Is controlled. As a result, the carriage 106 can be positioned at a predetermined position (note that even if there is a machine difference, the reference white plate 105 has a sufficient width, so there is no trouble in reading).

  In order to perform initialization control, when the carriage 106 reaches a predetermined position, the line sensor is activated (a readable operation mode), and the lighting of the document illumination unit 216 is controlled with a predetermined set light amount. At this time, if the reading result of the reference white plate 105 does not satisfy the conditions set by the image reading apparatus 101, the light level control of the original illumination unit or the output signal of the line sensor is amplified to set the reading level of the reference white plate 105. The level is adjusted to a level required by the image reading apparatus 101.

  Even in the case described above, when the reading level of the reference white plate 105 does not satisfy the predetermined condition, the image reading apparatus 101 determines that a hardware problem has occurred and displays an error display on the operation panel. .

  When the reading level of the reference white plate 105 satisfies a predetermined condition, an image processing unit (not shown) calculates a shading correction coefficient for correcting the reading level signal of the reference white plate 105 to be flat. After calculating the shading correction coefficient, the carriage 106 moves to the acceleration start position for scanning the document.

  The shading correction is executed in order to improve so-called edge light loss due to uneven sensitivity of the line sensor on the scanning line, uneven light distribution of the original illumination unit, and light collection characteristics of the optical system. While the carriage 106 moves, the control for turning on / off the document illumination unit should be changed according to the characteristics of the document illumination unit. In this case, when using a document illuminating unit that is stable and has a light quantity after lighting control that is equivalent to the light quantity level that was previously controlled to light, and that has good responsiveness, it is temporarily turned off from the viewpoint of power and heat generation, and the carriage 106 is accelerated. Move to the start position. Any method may be used as long as the image quality of the image reading apparatus 101 is not affected.

  In the illustrated example, the acceleration start position is not clearly defined. However, since it is desired to start scanning of the original 104 after the vibration of the carriage 106 is settled normally after entering the constant speed drive control, the position of the original 104 is set to the image destination position. The acceleration start position is set before the arrival. A position where acceleration is completed at least 10 mm to 20 mm before the image tip and constant speed control can be performed is set as an acceleration start position. That is, the acceleration start position is set at a position closer to the side plate of the image reading apparatus 101 than the flow-reading glass 103 and a position closer to the thread winding unit 121.

  When the original 104 is scanned, if the original 104 is A4 size, the original width is 210 mm. Therefore, if the optical motor 112 is driven with 2W1-2 phase excitation, as shown in Table 1, the optical motor 112 is 8 minutes. It is controlled by a step size of 0.0224 (mm / step) of the circumference.

  For example, pulse control is performed with 210 mm / 0.0224 mm = 9375 pulses (+ α) from the image tip, and then deceleration control is performed. For the return path, the carriage 106 is driven and controlled to return to the acceleration start position with the same number of pulses as the forward path.

  For the return path, when the flag 107 detects the HP sensor 108, stop control may be performed at a predetermined position set by the image reading apparatus 101. For example, after the flag 107 is detected by the HP sensor 108, the carriage 106 is decelerated, and after stopping, the carriage 106 is moved to the reading position of the reference white plate 105 and stopped. Alternatively, the carriage 106 may be stopped at the document size detection position of the document 104 set on the platen glass 102. Although there is no particular restriction on the document size detection position, the position moved from the image tip to the inside of the document by 10 mm to 20 mm is set as the fixed position in order to shorten the carriage movement time after size detection.

  FIG. 2 is a block diagram for explaining the hardware configuration of the image reading apparatus 101 shown in FIG.

  Referring to FIG. 2, the image reading apparatus has a control block 201, and the carriage 106 is driven and controlled by this control block 201. The control block 201 includes a control board 222, and a CPU 202, an image processing unit 203, a ROM 204, an EEPROM 205, and a motor driver 206 are mounted on the control board 222. The carriage 106 includes a sensor substrate 111, a document illumination unit 216, and a lens unit 218, and a sensor control IC 215, a line sensor 219, and an AFE 220 are mounted on the sensor substrate 111.

  The CPU 202 reads a control program from the ROM 204 and controls the motor driver 206 via the I / O (input / output) port of the image processing unit 203. Note that the motor driver 206 may be controlled using the I / O port of the CPU 202.

  The motor driver 206 drives the motor 112. Then, the carriage 106 is moved in the document scanning direction by the motor 112. The control block 201 and the carriage 106 are connected by a slidable connection cable 208. That is, the sensor board 111 and the control board 222 of the carriage 106 are connected by the slidable connection cable 208.

  When driving the carriage 106, as described above, the flag 107 provided on the carriage 106 is detected by the HP sensor 108 and the carriage position is initialized. Specifically, the HP 209 includes a light emitting unit and a light receiving unit. When light emitted from the light emitting unit is reflected by the flag 107, the reflected light is received by the light receiving unit and the flag 107 is detected ( (Indicated by reference numeral 209 in the figure).

  When the position of the carriage 106 is initialized, shading correction is also performed at the same time. At this time, the carriage 106 is moved to a position where the white plate 105 can be read, and the lighting of the document illumination unit 216 is controlled. The reflected light from the white plate 105 is condensed on the line sensor 219 via the lens unit 218 like the irradiation light indicated by reference numeral 217, and the scanning image of the white plate 105 is read. When the position of the carriage 106 is detected, the approximate position of the carriage 106 can be detected by reading the carriage position detection mark 213 set in the area outside the original of the platen glass 102. The sensor control IC 215 that performs the above control has a control I / O for the document illumination unit 216, and selectively controls partial lighting control and overall lighting control of the document illumination unit 216.

  The EEPROM 205 is a non-volatile backup memory, and stores adjustment values used in the image reading apparatus 101. In addition, correction values for correcting variations unique to the apparatus are also stored in the EEPROM 205.

  The image processing unit 203 performs serial communication with the sensor control IC 215 and the AFE (Analog Front End) 220 to set drive control of the carriage 106. The sensor control IC 215 drives and controls the line sensor 219 under the set conditions. The AFE 220 performs analog signal processing (sample hold) on the analog output of the line sensor 219, and then converts it into a digital signal by a built-in A / D converter (not shown). This digital signal is provided as a video signal to the image processing unit 203, and the image processing unit 203 executes various image processing such as the above-described shading correction in accordance with the video signal.

  FIG. 3 is a perspective view showing the structure (configuration) of the carriage 106 shown in FIG. FIG. 3A is a diagram showing the overall configuration of the carriage 106, and FIG. 3B is a diagram showing the configuration of a part of the carriage 106.

  With reference to FIG. 3, the carriage 106 includes an optical box 310, and the original illumination unit 216 and the sensor substrate 111 are mounted on the optical box 310. The sensor board 111 is connected to the cable 303 via the connector 304, and performs data communication with the control board 222 (FIG. 2) via the cable 303. Furthermore, power is supplied to the sensor substrate 111 via the cable 303.

  In the illustrated example, the document illumination unit 216 is an LED array light source in which a large number of LEDs (white LEDs) 309 are arranged in the main scanning direction (first direction), and the connector 305 is an LED array light source (document illumination unit 216). In addition, the LED 309 is controlled at a constant current through the feeder line 306. A reflector (reflector) 307 for improving the irradiation efficiency of the LED array light source 216 is disposed in the optical box 216. Yes.

  A reduction optical system is formed inside the optical box 310, and the reflected document light is guided so as to form an image on a line sensor (image reading unit: photoelectric conversion element) 219. In addition, a flag 107 is set in the optical box 310.

  FIG. 4 is a diagram for explaining the position detection of the carriage 106 in the image reading apparatus 101 shown in FIG.

  In the example shown in FIG. 4, an indicator plate 109 is provided on the scanning surface side of the platen glass 102 in case the flag 107 cannot be detected by the HP sensor 108. The indicator plate 109 has a mark 213 for detecting the position of the carriage 106. The mark 213 has a line segment extending in parallel from the white plate 105 and a line segment extending in a diagonal direction. The mark 213 is divided into two regions by line segments extending in the diagonal direction, and the two regions are color-coded as indicated by reference numeral 502.

  It is not necessary to color-code the two areas. In the illustrated example, the example in which the index plate 109 is formed on the platen glass 102 has been described. However, a ruled line may be formed on the scanning surface side of the upper frame of the image reading apparatus housing.

  FIG. 5 is a diagram for explaining position detection of the carriage 106 using the index plate 109 shown in FIG.

  Now, the number of pixels of the line sensor in the reduction optical system 219 is 7500 pixels. In this case, if the reading resolution of the image reading apparatus 101 is 600 dpi, a width of 317.25 mm can be read as the main scanning width 602. This dimension (that is, the main scanning width 602) has a margin of 20.25 mm even when the A4 main scanning width 604 (297 mm) is read when the A4 original 603 is set in accordance with the original abutting reference 607. It will be. That is, 317.25 mm−297 mm = 20.25 mm.

  Therefore, the width of the mark 213 is set to 10 mm at the sub-scanning position of the sub-scanning length 605 (420 mm) of the A3 document. In this case, the main scanning width 606 is 10 mm ÷ 42.3 μm≈236 pixels. Therefore, every time the main scanning width of the mark 213 changes by one pixel, the position in the sub-scanning direction (second direction) orthogonal to the main scanning direction is shifted by about 1.78 mm. That is, 420 mm ÷ 236 pixels≈1.78 mm / pixel.

  As a result, by reading ΔY, which is the difference between the parallel line segment and the diagonal line segment at the mark 213, the distance ΔX from the drawing destination of the carriage 106 can be obtained. That is, ΔX = ΔY × 1.78 mm.

  As described above, when the flag 107 cannot be detected by the HP sensor 108, the position of the carriage 106 can be roughly detected if the image reading apparatus 101 reads the mark 213.

  In the above example, the position of the carriage 106 is detected according to the parallel line segment and the diagonal line segment in the mark 213. For example, the mark 213 is not parallel to the sub-scanning direction (second direction). Moreover, it may have two line segments that are not parallel to each other. Also in this case, the position of the carriage 106 is detected according to the interval between two line segments that are not parallel to each other.

  FIG. 6 is a diagram for explaining drive control of the carriage 106 shown in FIG.

  In FIG. 6, the horizontal axis represents the distance in the sub-scanning direction of the image reading apparatus 101. The vertical axis represents the control speed (that is, movement speed). FIG. 6 shows the acceleration start position 701, the HP sensor 108 setting position 702, the image tip position 703, the A4 original trailing edge position 704, the A3 original trailing edge position 705, and the A3 original scanning time. A stop position 706 of the carriage 106 is shown.

  If the HP sensor 108 detects the flag 107 when the image reading apparatus 101 is activated, the carriage 106 is driven and controlled in the FWD direction (scanning direction of the document) 712. On the drive table image 707, HP 720, that is, the moment when the flag 107 is not detected by the HP sensor 108 is shown. After driving is stopped in the driving table image 707, the carriage 106 is controlled to move in the return (BACK) direction 711 by the driving table 708, and the HP sensor 108 is detected at a position 721 on the way. The carriage 106 samples the white plate 105 (not shown in FIG. 6) and moves to the acceleration start position 701.

  Although stop control may be performed at the shading position, in the illustrated example, a case where sampling during movement is performed will be described.

  The carriage 106 that has moved to the acceleration start position 701 scans an A3 document (not shown) in the forward (FWD) direction 712 by the drive table 709. On the way, the carriage 106 is switched from the acceleration control to the constant speed control at the position 713 before reaching the detection position 702 of the HP sensor 108, that is, the image tip position 703 (position for reading the leading edge of the document).

  The carriage 106 is decelerated after scanning the A3 document trailing edge 705 and stops at a position 706. After scanning the document image, the carriage 106 is controlled to move in the BACK direction 711 by the drive table 710, and detects the HP sensor 108 at a position 722. The carriage 106 is controlled to stop (decelerate) and stops at a predetermined position (reference position).

  Next, detection control of the HP sensor 108 when the carriage 106 is not stopped at a predetermined position when the power is turned on will be described. Here, in order to simplify the description, a case where the scanning range of the carriage 106 is divided into regions 714, 715, and 716 will be described.

  Here, the region 714 is a region where the carriage 106 is stopped near the HP sensor 108. In this area 714, since the position detection of the carriage 106 is performed as described above, the description is omitted. When the carriage 106 is stopped in the area 714, the carriage 106 is controlled to move in the BACK direction 711 by the drive table 717, the HP sensor 108 is detected at the position 723, and the carriage 106 is controlled to stop.

  Similarly, when the carriage 106 is stopped in the area 715, the carriage 106 is controlled to move in the BACK direction 711 by the drive table 718, the HP sensor 108 is detected at the position 724, and the carriage 106 is controlled to stop. The

  When the carriage 106 is stopped in the area 716, the carriage 106 is controlled to move in the BACK direction 711 by the drive table 719. When the carriage 106 detects the HP sensor 108 at the position 725, the carriage 106 is controlled to stop.

  As described above, since the drive tables 717, 718, and 719 have different control speeds, the difference in control speed is indicated in the vertical axis direction, and the drive speeds increase in the order of the drive tables 717, 718, and 719. In the area 714, the same control as the conventional control is imagined, but in reality, the relationship between the selected drive speed and the acceleration distance to reach the speed is important. Therefore, if acceleration control can be performed up to a desired drive speed at a distance from the stop position of the carriage 106 to the HP sensor 108, the drive control is performed at a higher speed to shorten the time required for the HP sensor 108 detection control. Like that. As a result, the total time for document scanning control can be shortened.

  As described above, if the carriage 106 can be controlled at a driving speed at which acceleration control can be completed at the distance for detecting the HP sensor 108 (calculated according to the position where the carriage 106 is roughly detected), There is no unstable drive control such as sudden start and stop that switches to stop control during acceleration. Further, it is possible to realize a high-speed and stable and quiet drive control, and to shorten the document scanning time.

  FIG. 7 is a diagram for explaining the document illumination unit 216 shown in FIG.

  As described above with reference to FIG. 7, in the illustrated example, as the document illumination unit 216, two LED array light sources in which a plurality of white LEDs 309 are arranged on a substrate are used. The document illumination unit 216 illuminates an illumination range 802 that is a document area. The document illumination unit 216 also illuminates illumination ranges 801 and 803 in the area outside the document. An illumination range 801 indicates an area outside the original on the side where the flag 107 is not present in the image reading apparatus 101, that is, the side where the index plate 109 is not present. An illumination range 803 indicates an area outside the original on the side where the index plate 109 is present. A portion surrounded by 805 shows a state where the LED 309 emits light by a broken line frame 805.

  When the image reading apparatus 101 scans the document (scanned object) 104 and reads an image on the document (scanned object), the document illumination unit 216 is controlled to turn on the entire area. For this reason, lighting of the document illumination unit 216 is controlled so that the light distribution characteristic 806 covers from the document region (scanning object region on which the scanning target object is placed) to the region outside the document. Here, in order to make the light distribution uniform light (flat) in the entire area of the document area 802, the illumination area has a space, and as a result, the light distribution extends flatly to the area outside the document.

  On the other hand, in the light distribution 807, only the area outside the document is illuminated when the position of the carriage 106 is detected. In the illustrated document outside area 811, a light distribution 808 outside the document, a position detection mark 213, and stop positions 809 and 810 of the carriage 106 are shown. Here, a sensor output image 812 of the line sensor 219 at the stop position 809 of the carriage 106 is shown. Similarly, a sensor output image 813 of the line sensor 219 at the stop position 810 of the carriage 106 is shown. These indicate the result of ΔX and ΔY scanning the position detection mark 213, and the stop position of the carriage 106 is calculated according to ΔX and ΔY.

  FIG. 8 is a diagram showing a configuration of an example of a lighting control circuit for controlling lighting of the document illumination unit 216 shown in FIG.

  Referring to FIG. 8, the lighting control circuit includes an LED power source 902 and a capacitor (capacitor) 903. The capacitor 903 is for improving the ripple of the LED power source 902. As described above, the document illumination unit 216 has a plurality of white LEDs 309. As shown in the figure, these white LEDs 309 are classified into a plurality of LED blocks 904, and each LED block 904 is turned on by an LED driver 906. Be controlled.

  Light amount control and lighting control in the LED block 904 are performed by the control circuit 901. Here, the control circuit 901 gives data (DATA), a clock (CLOCK), and a lighting signal (ON signal) to the LED driver 906, and executes light amount adjustment (light amount control) and lighting control of the LED block 904. In the illustrated example, only the LED driver 906 located at the left end is shown to receive the DATA, CLOCK, and ON signals. However, the DATA, CLOCK, and ON signals are all transmitted to the LED drivers 906. Given to.

  As illustrated, the lighting control circuit includes a selection circuit 911, and the control circuit 901 provides a selection circuit 911 lighting control signal (Edge LED ON signal). The selection circuit 911 performs lighting control of the LED block 906 located on the right side in the drawing in accordance with the lighting control signal or the ON signal (that is, whichever signal is received). The LED driver 906 located at the right end is for lighting the LED block 904 located in the area outside the document. That is, the LED block 906 located at the right end in the figure is controlled to be lit independently from the other LED blocks 906.

  FIG. 9 is a diagram for explaining the layout of the carriage position detection mark 213 shown in FIG.

  Referring to FIG. 9, in the image reading apparatus 101, when a general-purpose line sensor 219 is used, a scanable area outside the document area cannot be made sufficiently wide. Note that the readable area in the normal line sensor has already been described when the position detection of the carriage 106 is described. By the way, if a line sensor having a sufficient number of effective pixels is used, for example, an area outside the document in both the back and front directions of the platen glass can be used for carriage position detection.

  Normally, there is no room for setting a reading area on the front side of the outside area of the original, but when the line sensor 219 having a sufficient number of effective pixels is used, a scanning area can be provided on the front side of the outside area of the original. . In other words, the rear side uses the back side of the platen glass indicator plate, and the front side uses the ruled lines on the upper frame of the image reader, making it possible to detect the carriage position using multiple landmarks. Is alleviated.

  In general, an image reading apparatus is designed assuming carriage replacement. For this reason, the carriage 106 is normally removable, and a cutout is formed in the upper frame 1001 of the image reading apparatus 101 for extracting the carriage 106 along a path indicated by an arrow 1002. The location where the cutout is formed is not particularly limited, and the cutout portion can be provided only on one side.

  Considering the above points, the position detection mark of the carriage 106 is preferably formed on the back surface 1003 of the indicator plate 109. Further, since the platen glass is limited to the original scanning region, for example, if a position detection mark is provided on the scanning surface 1004 side of the upper frame 1001, the position detection mark of the carriage 106 over the entire area of the image reading apparatus. Can be arranged. As for the position detection of the carriage 106, the results of searching the outside-document area on both the back surface 1003 and the scanning surface 1004 are comprehensively determined. However, since the above-described position detection method object may be used, description thereof is omitted here.

  10A and 10B are flowcharts for explaining an example of the operation of the image reading apparatus 101 shown in FIG.

  2, 4, 5, 10 </ b> A, and 10 </ b> B, when the image reading apparatus 101 is turned on, the image reading apparatus 101 performs initialization (initialization). The positional relationship with the sensor 108 is confirmed (step S402). Then, the image reading apparatus 101 (that is, the CPU 202) determines whether or not the HP sensor 108 is in an ON state (step S403). If the HP sensor 108 is in the ON state (YES in step S403), the CPU 202 determines that the carriage 106 is stopped within the range of the flag 107 with respect to the HP sensor 108. Then, the CPU 202 controls the motor driver 206 via the image processing unit 203 to move the carriage 106 in the FWD direction. The CPU 202 detects again the position where the flag 107 deviates from the HP sensor 108 and adjusts the zero point of the carriage 106 (step S404).

  Subsequently, the CPU 202 controls the motor driver 206 via the image processing unit 203 to move the carriage 106 to the white plate 105 reading position (step S406). Then, the CPU 202 reads the white plate 105 via the line sensor 219, determines circuit system adjustment values such as the light amount and the gain adjustment value of the sensor signal system, and calculates a shading correction coefficient (step S407). Thus, when the initial adjustment is completed, the CPU 202 controls the motor driver 206 via the image processing unit 203 to move the carriage 106 to the standby position (step S408). Then, the CPU 202 stands by until an image reading JOB execution command is given.

  If the HP sensor is OFF in step S403 (NO in step S403), the CPU 202 sets the carriage 106 to an active state (original scanning mode) (step S410). That is, the CPU 202 operates the line sensor 219 via the sensor control IC 215. The AFE 220 reads the gain adjustment value determined at the time of initial adjustment, and the sensor control IC 215 controls the lighting of the document illumination unit 216. As a result, the CPU 202 prepares a state in which the document can be read.

  Subsequently, the CPU 202 sets a reading mode for an area outside the original that is not used during normal original reading (step S411). In other words, the CPU 202 controls the image processing unit 203 to set the reference area as an area outside the document and set the image processing range so that the position of the carriage 106 is not detected using wrong read information. . Then, the CPU 202 determines whether or not the carriage 106 is at a position away from a predetermined distance according to the reading value of the line sensor 219 in the outside area of the document (step S412).

  If the carriage 106 is separated from the predetermined distance (YES in step S412), the CPU 202 turns off the document illumination unit 216 via the sensor control IC 215 and stops reading the outside document area (step S413). . Then, the CPU 202 performs detection control of the HP sensor 108 using the fastest acceleration / drive table (first speed) in the drive control setting of the carriage 106 (step S414). Subsequently, the CPU 202 determines whether or not the HP sensor 108 is in an ON state (step S416). If HP sensor 108 is in the OFF state (NO in step S416), CPU 202 waits until HP sensor 108 is turned on.

  When the HP sensor 108 is in the ON state (YES in step S416), the CPU 202 switches the control of the carriage 106 to the deceleration / stop table and controls the carriage 106 to stop according to a predetermined number of pulses. After the carriage 106 stops, the CPU 202 proceeds to step S406 and controls the carriage 106 to move to the reading position of the white plate 105.

  If the carriage 106 is not separated from the predetermined distance in step S412, that is, if the distance is equal to or smaller than the predetermined distance (NO in step S412), the CPU 202 turns off the original illumination unit 216 via the sensor control IC 215. Then, reading of the area outside the document is stopped (step S418). Then, the CPU 201 performs detection control of the HP sensor 108 using the acceleration / drive table at the second speed lower than the first speed (step S419). Thereafter, the CPU 202 proceeds to step S416 to check whether the HP sensor 108 is in an ON state.

  In step S413, the document illumination unit 216 is turned off and reading of the document outside area is stopped. However, for example, the document illumination unit 216 may perform lighting control only on the document outside area. In this case, in order to detect the HP sensor 108, the area outside the document is scanned while the carriage 106 is moved. As a result, the position of the carriage 106 can be detected in real time. Therefore, since there is no correlation between the drive control of the carriage 106 and the read document image, the reliability in the drive control of the carriage 106 can be improved by associating the drive control of the carriage 106 with its position. It becomes possible.

  As described above, when it is detected that the carriage 106 is located at a position closer than a predetermined distance, drive control is performed at a second speed that is lower than the first speed. The reason for this is the relationship between the acceleration distance and the distance from the carriage 106 to the HP sensor 108. When the acceleration distance is longer than the distance from the carriage 106 to the HP sensor 108, the drive control of the carriage 106 is a jerky drive control such as sudden start or stop. This point is not suitable for quiet drive control, and the drive system may step out. Therefore, in the illustrated example, the carriage 106 drive control is performed at an optimum speed according to the stop position of the carriage 106 to reduce the return time to the HP sensor 108 and to perform the silent control with a reliable drive. ing.

  FIG. 11 is a diagram for explaining another example of the layout of the carriage position detection mark shown in FIG. FIG. 11A is a diagram showing an example of a state in which density marks 1201 to 1209 are arranged on the scanning surface side of the document index plate 109, and FIG. It is a figure which shows the other example of the state which arranged the marks 1210 and 1211.

  First, referring to FIG. 11A, here, density marks 1201 to 1209 having different density levels are formed on the document index plate 109. That is, in the illustrated example, nine density marks 1201 to 1209 are formed, and after the density marks 1209 are not colored, the color of the document index plate 109 itself appears. Therefore, all ten types of density marks are attached.

  For example, if the reading resolution in the image reading apparatus 101 is 8 bits, the density marks 1201 to 1209 are formed with a luminance level difference of about 25 levels obtained by dividing 256 gradations into 10 equal parts. The density variation between the density marks 1201 to 1209 does not have to be exact, and can be used for detecting the position of the carriage 106 if the luminance density is arranged in order from the density mark 1201.

  By the way, when the movement control of the carriage 106 is performed, if the high-speed movement control is performed, a sufficient acceleration distance may not be obtained. For this purpose, it is only necessary to prepare a carriage position detecting means (that is, a density mark here) only in an area where acceleration control is difficult.

  Referring to FIG. 11B, density marks 1210 and 1211 are arranged on the scanning surface side of the document index plate 109 on the platen glass 102. Here, it is detected by the density marks 1210 and 1210 that the carriage 106 is positioned in the vicinity of the HP sensor 108. When the carriage 106 is away from the HP sensor 108, control for returning the carriage 106 to the HP sensor 108 is executed.

  In the illustrated example, in order to shorten the movement time of the carriage 106, the movement speed of the carriage is switched according to the position information detected by the carriage position detection means. However, the carriage position detection means is stopped when the carriage is stopped. It is possible to make it function besides. For example, if the position of the carriage 106 does not change even if the movement control of the carriage 106 is performed, it is possible to detect that a problem has occurred in the drive control system. If a detection result is displayed on the operation panel when a failure occurs in the drive control system, it can be used to isolate the cause of the failure.

  In this manner, in the above-described embodiment, the carriage position detection mark formed in the area outside the document that can be scanned by the carriage 106 is read at the time of startup such as when the power is turned on (prior to the image reading operation). The carriage position is detected. As a result, the carriage 106 can be moved at an optimum speed according to the distance between the HP and the carriage position.

  Further, as a carriage position detection mark, for example, a ruled line provided on the reading surface of the line sensor of the upper frame of the image reading device or a line segment formed on the back surface of the document size indicator plate set on the platen glass is used. I use it. For this reason, there is also an advantage that the cost increase is small.

  When a wire and a belt are used for the drive transmission unit of the carriage 106, a problem such as disconnection of the wire may occur. In the above-described embodiment, since the carriage position is detected, that is, the movement of the carriage can be known, the above-described problem can be quickly detected.

  As described above, according to the image reading apparatus according to the present embodiment, the position of the carriage 106 is detected at the start of the image reading apparatus such as when the power is turned on without increasing the cost. The carriage can be moved to the HP by the optimum drive control according to the response. As a result, there is an effect that it is possible to shorten the time until the document is scanned.

  Furthermore, even if the carriage 106 is driven at a high speed, there is no fear that the driving sound will increase, and smooth start-up control can be realized in a short time.

  Further, since the position information of the carriage 106 can be confirmed in real time, the moving speed of the carriage can be known in accordance with the scanning information of the area outside the document, and as a result, a driving failure of the carriage 106 can be detected. .

  As is apparent from the above description, in this embodiment, steps S401 and S402 function as reference position detection means, and steps S410 and S411 function as carriage position detection means (carriage position acquisition means). Steps S406 to S408 function as initialization control means, and steps S412 to S419 function as movement control means.

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to these embodiment, Various forms of the range which does not deviate from the summary of this invention are also contained in this invention. .

  For example, the functions of the above embodiments may be used as an image reading control method, and the image reading control method may be executed by a computer included in the image reading apparatus. At this time, the image reading control method includes at least a reference position step, a carriage position detection step, an initialization control step, and a movement control step.

  Further, software (program) that realizes the functions of the above-described embodiments may be supplied to a system or an apparatus via a network or various computer-readable recording media. Then, a computer (or CPU, MPU, etc.) of the system or apparatus may read and execute the program.

105 Reference White Plate 106 Carriage 107 Flag 108 HP (Home Position) Sensor 109 Index Plate 202 CPU
203 Image Processing Unit 213 Carriage Position Detection Mark 216 Document Illumination Unit 219 Line Sensor

Claims (8)

An image reading unit extending in a first direction is provided, the object to be scanned is scanned by moving in a second direction orthogonal to the first direction, and an image on the object to be scanned is scanned by the image reading unit. In an image reading apparatus having a scanning carriage for reading
Reference position detection means for detecting whether or not the scanning carriage is positioned at a predetermined reference position;
Carriage position detecting means for detecting a position of the scanning carriage in the second direction as a carriage position;
Prior to the image reading operation, when the reference position detecting means detects that the scanning carriage is located at the reference position, initialization control means for executing predetermined initialization control;
Prior to the image reading operation, if the reference position detection unit does not detect that the scanning carriage is positioned at the reference position, the distance between the carriage position and the reference position is greater than a predetermined distance. In this case, movement control means for moving the scanning carriage in the direction of the reference position with a higher moving speed of the scanning carriage than in the case where the distance between the carriage position and the reference position is equal to or less than the predetermined distance. An image reading apparatus comprising: The scanning carriage is scanned in a range wider than a scanning target area on which the scanning target is placed,
The carriage position detecting means is formed outside the scanning object region and extends in the second direction;
The image reading apparatus according to claim 1, further comprising a carriage position obtaining unit that obtains the carriage position according to a result of reading the position detection mark by the image reading unit. Having a platen glass on which the object to be scanned is placed;
The image according to claim 2, wherein the position detection mark is formed on an index plate that extends in the second direction and is used as an index when the object to be scanned is arranged on the platen glass. Reader. The position detection mark intersects the parallel line segment extending in the second direction and the parallel line segment at the scanning start position of the object to be scanned, and the parallel detection is performed from the scanning start position toward the second direction. A diagonal segment away from the line segment,
4. The image reading apparatus according to claim 2, wherein the carriage position obtaining unit obtains the carriage position in accordance with an interval between the parallel line segment and the diagonal line segment. The position detection mark has two line segments not parallel to the second direction and not parallel to each other,
4. The image reading apparatus according to claim 2, wherein the carriage position obtaining unit obtains the carriage position in accordance with an interval between the two line segments that are not parallel to each other.   4. The image reading apparatus according to claim 2, wherein the position detection mark is a density mark that extends along the second direction and whose density level varies depending on the position in the second direction. .   When the distance between the carriage position and the reference position is greater than a predetermined distance, the movement control unit moves the scanning carriage at a predetermined first speed, and the carriage position and the reference position 7. The image according to claim 1, wherein the scanning carriage is moved at a second speed lower than the first speed when the distance is equal to or less than the predetermined distance. Reader. An image reading unit extending in a first direction is provided, the object to be scanned is scanned by moving in a second direction orthogonal to the first direction, and an image on the object to be scanned is scanned by the image reading unit. In an image reading control method for controlling an image reading apparatus having a scanning carriage for reading
A reference position step for detecting whether or not the scanning carriage is located at a predetermined reference position;
A carriage position detecting step for detecting a position of the scanning carriage in the second direction as a carriage position;
Prior to the image reading operation, when it is detected by the reference position detection step that the scanning carriage is positioned at the reference position, an initialization control step for executing a predetermined initialization control;
Prior to the image reading operation, if it is not detected by the reference position detection step that the scanning carriage is positioned at the reference position, the distance between the carriage position and the reference position is greater than a predetermined distance. In this case, the movement control step of moving the scanning carriage in the direction of the reference position at a higher moving speed of the scanning carriage than in the case where the distance between the carriage position and the reference position is equal to or less than the predetermined distance. An image reading method comprising:

Images