JP4631835B2 - Image reading apparatus and image reading method - Google Patents

Description

  The present invention relates to an image reading apparatus and an image reading method for reading an image from a document by a sensor that moves relative to the document.

Various image reading apparatuses such as an image scanner include an image reading sensor such as an image sensor for reading an image from a document. The image reading sensor moves relative to the document when reading an image from the document. Here, the image reading sensor sequentially outputs image data read from the document while moving relative to the document. The timing at which the image data read from the document is output from the image reading sensor is determined based on the moving distance and moving speed of the image reading sensor. That is, the timing at which image data read from the document is output from the image reading sensor is changed in accordance with the moving distance or moving speed of the image reading sensor. As a result, even when the moving speed of the image reading sensor fluctuates, an image can be properly read from the document at a predetermined pitch (see Patent Document 1).
Japanese Patent No. 9-269633

  However, when the moving speed of the image reading sensor suddenly increases due to an external impact or the like while reading an image from a document, the following problem occurs. That is, since the movement speed of the image reading sensor suddenly increases, the data output from the image reading sensor cannot be acquired in time, and the image cannot be read properly from the document. As described above, when an image cannot be read from a document, the quality of the read image is deteriorated.

  The present invention has been made in view of such circumstances, and an object of the present invention is to enable smooth detection when the moving speed of a sensor that reads an image from a document suddenly increases. There is.

The main invention for achieving the object is as follows:
(A) an image reading sensor that moves relative to the document and reads an image from the document;
(B) a signal output unit that outputs a signal corresponding to a relative movement of the image reading sensor with respect to the document;
(C) A timing signal that defines a reference timing for acquiring data of the image read from the document by the image reading sensor from the image reading sensor based on the signal output from the signal output unit. A timing signal generator for generating
(D) When the timing defined by the timing signal generated by the timing signal generation unit is less than a predetermined time with respect to the previous timing, the image data from the image reading sensor A determination unit that determines that an error has occurred and acquisition has not been completed,
Equipped with a,
When the determination unit determines that the error has occurred, the image reading operation for reading an image from the document by the image reading sensor is stopped, and the image reading operation is resumed from a position before the error is determined. An image reading apparatus characterized by the above.

  Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

  At least the following matters will become apparent from the description of the present specification and the accompanying drawings.

(A) an image reading sensor that moves relative to the document and reads an image from the document;
(B) a signal output unit that outputs a signal corresponding to a relative movement of the image reading sensor with respect to the document;
(C) A timing signal that defines a reference timing for acquiring data of the image read from the document by the image reading sensor from the image reading sensor based on the signal output from the signal output unit. A timing signal generator for generating
(D) When the timing defined by the timing signal generated by the timing signal generation unit is less than a predetermined time with respect to the previous timing, the image data from the image reading sensor A determination unit that determines that an error has occurred and acquisition has not been completed,
An image reading apparatus comprising (E).

  In such an image reading apparatus, when the interval between the timing specified by the timing signal generated by the timing signal generation circuit and the previous timing is less than a predetermined time, the image reading sensor When the determination unit determines that the image data acquisition has not been completed and the determination unit determines that the error has occurred, the movement speed of the image reading sensor suddenly increases due to an external impact or the like, and the data acquisition from the image reading sensor is not in time This can be detected.

  In such an image reading apparatus, the signal output unit may output a signal corresponding to a relative moving speed of the image reading sensor with respect to the document as the signal. As described above, the signal output unit outputs a signal corresponding to the relative moving speed of the image reading sensor with respect to the document as a signal, so that the timing signal can be easily generated by the timing signal generation circuit.

  In the image reading apparatus, the signal output unit may output a signal corresponding to a relative movement distance of the image reading sensor with respect to the document as the signal. As described above, the signal output unit outputs a signal according to the relative movement distance of the image reading sensor with respect to the document as a signal, so that the timing signal can be easily generated by the timing signal generation circuit.

  In such an image reading apparatus, the signal output unit may include an encoder for outputting the signal. As described above, if the signal output unit includes an encoder for outputting a signal, a signal corresponding to the relative movement distance of the image reading sensor with respect to the document can be easily output from the signal output unit.

  In the image reading apparatus, the predetermined time may be set to be longer than a time necessary for acquiring the image data from the image reading sensor. In this way, if the predetermined time is set to be longer than the time necessary for acquiring image data from the image reading sensor, the moving speed of the image reading sensor suddenly increases due to an external impact or the like. This can be quickly detected when the data acquisition is not in time.

  In the image reading apparatus, when the error is determined by the determination unit, the image reading operation for reading an image from the document by the image reading sensor is stopped, and the error before the error is determined. The image reading operation may be resumed from the position. When the determination unit determines that an error has occurred, the image reading operation for reading an image from the document by the image reading sensor is stopped, and the image reading operation is restarted from the position before the error is determined. Images can be read from the original.

  In the image reading apparatus, the determination unit includes a timer that measures an elapsed time from the occurrence of the timing defined by the timing signal generated by the timing signal generation circuit. Also good. If the determination unit includes such a timer, it is simply checked whether or not the interval between the previous timing and the timing specified by the timing signal generated by the timing signal generation unit is less than a predetermined time. be able to.

  In this image reading apparatus, the relative moving speed of the image reading sensor with respect to the document may be changed after the determination unit determines that the error has occurred. In this way, when an error is determined by the determination unit, it is possible to prevent the determination unit from determining an error by changing the target value of the relative movement speed of the image reading sensor with respect to the document.

(A) a step of moving an image reading sensor relative to an original to read an image from the original;
(B) outputting a signal corresponding to a relative movement of the image reading sensor with respect to the document;
(C) generating a timing signal that defines a reference timing for acquiring data of the image read from the document by the image reading sensor from the image reading sensor based on the output signal;
(D) The acquisition of the image data from the image reading sensor is not completed when the interval defined by the generated timing signal is less than a predetermined time with respect to the previous timing. And determining an error as
An image reading method comprising (E).

=== Overview of Image Reading Apparatus ===
Embodiments of an image reading apparatus according to the present invention will be described below. 1 to 3 illustrate an embodiment of an image reading apparatus. FIG. 1 illustrates an embodiment of an image reading apparatus. FIG. 2 is a diagram illustrating an example of the internal configuration of the image reading apparatus. FIG. 3 is a diagram illustrating an example of a block configuration of the image reading apparatus.

  As shown in FIG. 1, the image reading device 10 is connected to a computer device 20 so as to be communicable by wire or wireless. Here, as shown in FIG. 1, the image reading apparatus 10 is an apparatus generally called an image scanner, and includes a document table 12 and a document table cover 14 that opens and closes the upper surface of the document table 12. A document 15 from which an image is read is set on the document table 12. The document table cover 14 is provided at the rear end portion of the document table 12 through a hinge portion 18 so as to be freely opened and closed.

  On the other hand, as shown in FIG. 1, for example, the computer device 20 includes a computer main body 22, a display device 24, and an input device 26. The computer main body 22 includes various computers such as a personal computer. Here, the computer main body 22 includes a reading device 32 such as an FD drive device 28 or a CD-ROM drive device 30 therein. In addition, the computer main body 22 may include, for example, an MO (Magnet Optical) disk drive device or a DVD drive device. The display device 24 includes various display devices such as a CRT display, a plasma display, and a liquid crystal display. The input device 26 includes a keyboard 34, a mouse 36, and the like.

<Image reading device>
As shown in FIG. 2, the image reading apparatus 10 includes a carriage 40 and a drive mechanism that moves the carriage 40 in parallel along the direction of arrow A in the figure while maintaining a predetermined distance from the document table 12. 42 and a guide 44 for guiding the movement of the carriage 40 while supporting it.

  The carriage 40 has an exposure lamp 46 as a light source for irradiating light to the document 15 via the document table 12, a lens 48 on which reflected light reflected by the document 15 is incident, and the inside of the carriage 40 through the lens 48. And an image sensor 50 for receiving the reflected light taken in. The image sensor 50 includes a linear CCD sensor or the like in which photoelectric conversion elements such as photodiodes that convert optical signals into electric signals are arranged in a line. The image sensor 50 corresponds to an “image reading sensor”. The image data read by the image sensor 50 is output to the control unit 52.

  The drive mechanism 42 includes a timing belt 54 connected to the carriage 40, a pair of pulleys 55, 56 around which the timing belt 54 is stretched, and a drive motor 58 that rotationally drives one pulley 55. Yes. The drive motor 58 is driven and controlled by a control signal from the control unit 52.

  Further, the drive mechanism 42 is provided with an encoder 90 in the vicinity of the drive motor 58. The encoder 90 is a rotary encoder, and detects the position, moving distance, moving speed, and the like of the carriage 40 by detecting the rotation amount of the drive motor 58. The encoder 90 includes an encoder code plate 92 provided integrally with the rotation shaft of the drive motor 58, and a detection unit 94 provided adjacent to the encoder code plate 92. A large number of small slits (not shown) are formed at predetermined intervals on the outer peripheral edge of the encoder code plate 92. The detector 94 detects slits (not shown) provided on the outer peripheral edge of the encoder code plate 92 and outputs pulse signals ENC-A and ENC-B corresponding to the rotation amount of the drive motor 58. The encoder 90 corresponds to a “signal output unit”.

<Control unit>
As shown in FIG. 3, the control unit 52 includes a controller 60, a motor control unit 62, a lamp control unit 64, a sensor control unit 66, an AFE (Analog Front End) unit 68, a digital processing circuit 70, And an interface circuit 72. Further, the AFE (Analog Front End) unit 68 includes an analog signal processing circuit 74 and an A / D conversion circuit 76.

  The controller 60 controls the motor control unit 62, the lamp control unit 64, the sensor control unit 66, the AFE (Analog Front End) unit 68, the digital processing circuit 70, and the interface circuit 72 based on commands from the computer main body 22. The motor control unit 62 performs drive control of the drive motor 58 for moving the carriage 40 according to a command from the controller 60. The lamp control unit 64 controls the light emission of the exposure lamp 46. The sensor control unit 66 controls the image sensor 50.

  An analog signal processing circuit 74 of an AFE (Analog Front End) unit 68 performs signal processing on an analog signal of an image read by the image sensor 50. An A / D conversion circuit 76 of an AFE (Analog Front End) unit 68 performs A / D conversion on the image signal processed by the analog signal processing circuit 74 into a digital signal.

  The digital processing circuit 70 performs digital signal processing on the digital signal sent from the A / D conversion circuit 76 of the AFE (Analog Front End) unit 68. Here, specifically, various image processing and the like are performed, including correction processing such as shading correction. The digital signal subjected to the digital signal processing is output as image data (image data) read from the document 15 to the outside, that is, to the computer main body 22 to which the image reading apparatus 10 is connected in this case. The In addition to this, the interface circuit 72 receives commands (commands) and the like from the computer main body 22 to the image reading apparatus 10.

=== Exposure lamp ===
The exposure lamp 46 includes LED lamps of three colors of red (R), green (G), and blue (B). These RGB three-color LED lamps are turned on at different timings when the image sensor 50 reads an image from the document 5. That is, for example, the three color LED lamps are lit in the order of red (R) → green (G) → blue (B).

  FIG. 4 explains an example of the light emission order of the three-color LED lamps. As shown in the figure, the exposure lamps 46 are individually lit at different timings within the period of one cycle. The LED lamps of the respective colors are turned on for predetermined times Tr, Tg, and Tb set in advance within a period of one cycle. In order to turn on these three color LED lamps for predetermined times Tr, Tg, and Tb, respectively, a total exposure time Tw is required per cycle.

=== Image sensor ===
FIG. 5 illustrates an example of a photoelectric conversion element provided in the image sensor 50. As shown in the figure, the image sensor 50 according to the present embodiment includes a plurality of photodiodes 80 arranged in a line along a predetermined direction, and a charge transfer unit 82 (CCD: charge). -coupled device) and a plurality of gates 84 provided between the plurality of photodiodes 80 and the charge transfer unit 82, respectively.

  Electric charges are generated in the plurality of photodiodes 80 according to the amount of received light. In the present embodiment, each of the plurality of photodiodes 80 receives light emitted from the exposure lamp 46 and reflected from the document 15 placed on the document table 12. That is, each photodiode 80 receives light of three colors emitted from the exposure lamp 46, that is, light of each color of red (R), green (G), and blue (B). The plurality of photodiodes 80 generate charges P corresponding to the amounts of light of the three colors received.

  The charge P generated in each photodiode 80 is transferred to the charge transfer unit 82. When the charge P generated in each photodiode 80 is transferred to the charge transfer unit 82, each gate 84 (see the gray portion in the figure) is opened. The charge P generated in each photodiode 80 quickly moves to the charge transfer unit 82 due to the potential well relationship.

  The charge transfer unit 82 temporarily accumulates the charge P that has moved from each photodiode 80 and then sequentially transfers the charge P toward the detection circuit 86. The detection circuit 86 sequentially detects the amount of charge transferred by the charge transfer unit 82. Here, the charge amount of the charge P detected by the detection circuit 86 becomes data for one pixel constituting the image of the document 15 on the document table 12 read by the image sensor 50. The detection circuit 86 outputs the detection result of the charge amount of the transferred charge P to an AFE (Analog Front End) unit 68 (see FIG. 3).

=== Conventional Problems and Solutions ===
<Conventional problems>
By the way, such an image reading apparatus 10 has the following problems. In other words, when the moving speed of the image sensor 50 suddenly increases due to an external impact or the like while reading an image from the document 15, the data output from the image sensor 50 is not acquired in time, and the document 15 is neatly acquired. The image could not be read. As described above, when the image cannot be read from the document 15, the quality of the read image is deteriorated.

<Solution>
Therefore, in the present embodiment, when the moving speed of the image sensor 50 suddenly increases due to an external impact or the like while reading an image from the document 15, this is immediately detected as an error. When such an error occurs, it is dealt with promptly.

=== Timing signal ===
The control unit 52 is provided with a timing signal output circuit 110 that outputs a timing signal that defines the timing of light emission by the exposure lamp 46 and the timing of reading an image by the image sensor 50.

  FIG. 6 illustrates the timing signal output circuit 110. The timing signal output circuit 110 is controlled by the controller 60 of the control unit 52 as shown in FIG. The timing signal output circuit 110 receives an output signal from the encoder 90, that is, pulse signals ENC-A and ENC-B. The timing signal output circuit 110 generates a timing signal St based on these pulse signals ENC-A and ENC-B input from the encoder 90.

  FIG. 7 illustrates an example of the timing signal St generated by the timing signal output circuit 110. The timing signal St is generated based on the edges of the pulse signals ENC-A and ENC-B output from the encoder 90, as shown in FIG.

  Here, the pulse signals ENC-A and ENC-B are signals output from the detection unit of the encoder, and are out of phase with each other by 90 degrees. The phase of the pulse signal ENC-A is advanced by 90 degrees from the pulse signal ENC-B when the drive motor 58 is rotating forward. On the other hand, when the drive motor 58 is reversed, the phase of the pulse signal ENC-A is delayed by 90 degrees from the pulse signal ENC-B. One cycle Tp of each of the pulse signals ENC-A and ENC-B is the distance between the rotation shaft of the drive motor 58 and the slit 96 of the encoder code plate 92 (for example, 1/2400 inch, 1/1200 inch, 1/600 inch, etc. (1 inch = 2.54 cm)) is equal to the rotation time.

  From this, if the edges are detected from the pulse signals ENC-A and ENC-B output from the encoder 90, the rotational speed of the drive motor 58 can be acquired. Therefore, the moving speed of the carriage 40 can be detected. If the number of edges is counted, the amount of rotation of the drive motor 58 can be examined. Thereby, the current position of the carriage 40 can also be detected.

  In the present embodiment, the timing signal generation circuit 112 generates the timing signal St based on the rising edge of the pulse signal ENC-A. In the timing signal St generated here, a pulse Wt is generated corresponding to the timing at which a rising edge occurs in the pulse signal ENC-A.

  The timing signal St thus generated is output from the timing signal output circuit 110 to the lamp control unit 64 and the sensor control unit 66 as shown in FIG. The lamp control unit 64 and the sensor control unit 66 control the exposure lamp 46 or the image sensor 50 based on the timing signal St output from the timing signal output circuit 110.

  Here, based on the timing signal St output from the timing signal output circuit 110, the lamp control unit 64 has three colors of LEDs, that is, a red (R) LED lamp, a green (G) LED lamp, and a blue ( The timing for turning on the LED lamp of B) is controlled. Specifically, the lamp control unit 64 determines that the timing signal St output from the timing signal output circuit 110 is 3 within the lighting time Tw after the pulse Wt is generated until the next pulse Wt is generated. The color LED lamps are lit in the order of, for example, red (R) → green (G) → blue (B).

  On the other hand, the sensor control unit 66 controls the timing of acquiring the accumulated charges from the plurality of photodiodes 80 provided in the image sensor 50 based on the timing signal St output from the timing signal output circuit 110. Specifically, the sensor control unit 66 opens the gates 84 with reference to the timing at which the pulse Wt is generated in the timing signal St output from the timing signal output circuit 110, and a plurality of sensors provided in the image sensor 50 are provided. The charges accumulated in the photodiodes 80 are moved to the charge transfer section 82 (see FIG. 5). Here, the sensor control unit 66 emits light of three colors, that is, red (R), green (G), and blue (B) in a predetermined order from the exposure lamp 46 by the lamp control unit 64. Each time the charges accumulated in the plurality of photodiodes 80 are moved to the charge transfer unit 82. That is, the charge moves from each photodiode 80 to the charge transfer unit 82 three times. As a result, the sensor control unit 66 detects, in the detection circuit 86, the electric charges accumulated in the plurality of photodiodes 80 for each color of light emitted from the exposure lamp 46. Here, for the three colors of red (R), green (G), and blue (B), the charge generated in each photodiode 80 is moved to the charge transfer unit 82 and is detected by the charge transfer unit 82. The time required to transfer to is shown as time Ts.

  In this way, the lamp control unit 64 and the sensor control unit 66 control the exposure lamp 46 or the image sensor 50 based on the timing signal St output from the timing signal output circuit 110.

  Note that the pulse signals ENC-A and ENC-B output from the encoder 90 are also input to the motor control unit 62 as shown in FIG. The motor control unit 62 acquires information on the moving speed and moving distance (current position) of the carriage based on the pulse signals ENC-A and ENC-B output from the encoder 90, and the drive motor 58 is based on these information. To control.

=== Error judgment ===
In this embodiment, when the moving speed of the image sensor 50 suddenly increases due to an external impact or the like while reading an image from the document 15, the timing signal output circuit 110 is detected in order to detect this as an error. The following configuration is provided.

  FIG. 8 illustrates an example of the configuration of the timing signal output circuit 110. FIG. 9 explains each signal generated by the timing signal output circuit 110.

  The timing signal output circuit 110 includes a timing signal generation circuit 112, a mask timer 114, and a mask circuit 116 (see FIG. 8). The timing signal generation circuit 112 generates the original signal S0 based on the pulse signals ENC-A and ENC-B output from the encoder 90 (see FIG. 9). The timing signal generation circuit 112 corresponds to a “timing signal generation unit”. The original signal S0 generated here is a reference signal for the timing signal St output from the timing signal output circuit 110, and is based on the edges of the pulse signals ENC-A and ENC-B output from the encoder 90. Generated. Here, based on the rising edge of the pulse signal ENC-A, the original signal S0 is generated. That is, the original signal S0 is provided with a pulse Wt0 generated corresponding to the timing at which a rising edge occurs in the pulse signal ENC-A.

  The original signal S0 generated and output by the timing signal generation circuit 112 is input to the mask timer 114. The mask timer 114 includes a timer (not shown) that measures an elapsed time after the timing is generated in the original signal S0 output from the timing signal generation circuit 112. The mask timer 114 measures an elapsed time after the timing is generated in the original signal S0 by this timer, and outputs a mask signal Sm for masking the original signal S0 until the elapsed time reaches a predetermined time. Generate (see FIG. 9). The mask signal Sm generated here is, for example, a signal whose signal level becomes “H (high)” from the generation of the pulse Wt0 of the original signal S0 to the elapse of a predetermined time Tm. The mask timer 114 starts time measurement by the timer and generates a mask signal Sm each time a timing defined by the original signal S0 output from the timing signal generation circuit 112 occurs.

  The mask circuit 116 masks the original signal S0 output from the timing signal generation circuit 112 with the mask signal Sm output from the mask timer 114. That is, the mask circuit 116 ignores the timing after the timing defined by the original signal S0 and the interval with the previous timing is shorter than the predetermined time. As a result, the mask circuit 116 has removed the timing after the interval shorter than the predetermined time from the timing specified by the original signal S0 output from the timing signal generation circuit 112. The signal is output to the outside as a timing signal St.

  The mask circuit 116 is masked by the mask signal Sm output from the mask timer 114, that is, here, for a predetermined time Tm in which the signal level of the mask signal Sm is “H (high)”. When the next timing occurs in the original signal S0 output from the timing signal generation circuit 112, the image sensor 50 determines that the acquisition of the image data from the document has not been completed, and the controller 60 is informed. Output an error signal.

<Predetermined time Tm>
Here, the predetermined time Tm will be described. The predetermined time Tm is preferably set as follows.

(A) Time More than Time Ts Required for Charge Transfer by Charge Transfer Unit 82 If the predetermined time Tm is set as the time Ts required for charge transfer by the charge transfer unit 82 as the mask period of the mask signal Sm, the timing is reached. The interval between the pulse Wt0 generated corresponding to the timing defined by the original signal S0 output from the signal generation circuit 112 and the pulse Wt0 generated corresponding to the previous timing is the charge transfer unit 82. This can be detected as an error when it is shorter than the time Ts required to transfer the charges. As a result, when a problem occurs in the operation of reading an image from the document by the image sensor 50, this can be detected smoothly.

(B) Time equal to or longer than the total lighting time Tw of the exposure lamp 46 If the predetermined time Tm is set longer than the set time Tw of the exposure lamp 46 as the mask period of the mask signal Sm, the timing signal generating circuit 112 The interval between the pulse Wt0 generated corresponding to the timing defined by the output original signal S0 and the pulse Wt0 generated corresponding to the previous timing is the LED lamp of each RGB color of the exposure lamp 46 This can be detected as an error when it is shorter than the total lighting time Tw. As a result, when a problem occurs in the operation of reading an image from the document by the image sensor 50, this can be detected smoothly.

  For the requirements (A) and (B), the predetermined time Tm may be set so as to satisfy only one of them, or the predetermined time Tm is set so as to satisfy both requirements. good. Preferably, the predetermined time Tm is set so as to satisfy at least the requirement (A).

=== Action to be taken when an error is detected ===
<Reread>
When the controller 60 receives the error signal output from the mask circuit 116 of the timing signal output circuit 110, the controller 60 determines that an abnormality has occurred in the operation of reading an image from the document by the image sensor 50, and the motor control unit 62. Then, the drive of the drive motor 58 is stopped and the movement of the carriage 40 is temporarily suspended.

  Thereafter, the controller 60 reversely rotates the drive motor 58 through the motor control unit 62 to retract the carriage 40 by a predetermined distance. Here, the predetermined distance for moving the carriage 40 backward is a preset distance. The distance set in advance here basically depends on the moving speed of the carriage 40 (rotational speed of the drive motor 58).

  In this way, the controller 60 moves the carriage 40 backward by a predetermined distance, and then forwardly drives the drive motor 58 through the motor control unit 62 to advance the carriage 40 again. Then, the image reading operation is started again from the position where the image reading operation was interrupted.

<Change speed setting>
Here, when the controller 60 receives the error signal output from the mask circuit 116 of the timing signal output circuit 110 and restarts the image reading operation from the position where the image reading operation is interrupted, the restarted image reading is performed. If the target moving speed of the carriage 40 is set to a lower speed in the operation, it is possible to prevent the error from occurring again. Here, the newly set low speed can be set to a value obtained by reducing the speed by a predetermined ratio from the target moving speed of the carriage 40 before the error occurs.

=== Summary ===
As described above, in the present embodiment, the timing signal output circuit 110 corresponds to the timing defined by the original signal S0 generated by the timing signal generation circuit 112 based on the pulse signals ENC-A and ENC-B output from the encoder 90. When the interval between the pulse Wt0 generated in this way and the pulse Wt0 generated corresponding to the previous timing is shorter than the predetermined time Tm, this can be detected as an error. Therefore, when the moving speed of the image sensor 50 suddenly increases due to an external impact or the like while reading an image from the document 15, this can be promptly detected as an error.

=== Other Embodiments ===
As described above, the embodiment has been described. However, the above-described embodiment is for facilitating the understanding of the present invention, and is not intended to limit the present invention. The present invention can be changed or improved without departing from the gist thereof, and needless to say, the present invention includes equivalents thereof. In particular, the embodiments described below are also included in the present invention.

<About image reading sensor>
In the above-described embodiment, the image sensor 50 provided in the carriage 40 has been described as an example of the “image reading sensor”. However, in the “image reading sensor” here, such a carriage 40 is not necessarily used. It is not restricted to the sensor provided in. That is, any type of sensor may be used as long as the sensor moves relative to the document 15 and reads an image from the document. That is, a sensor that reads an image from a document by moving the document relative to the “image reading sensor” may be included.

  In the “image reading sensor” here, the image sensor 50 including a plurality of photodiodes 80 is described as an example of the photoelectric conversion element. However, in the “image reading sensor” herein, Is not necessarily limited to a sensor having a plurality of such photodiodes 80. That is, any type of sensor may be used as long as it reads an image from a document. That is, any method for reading an image from the document 15 may be used.

<Signal output unit>
In the above-described embodiment, the encoder 90 that outputs the pulse signals ENC-A and ENC-B having a period corresponding to the moving speed of the carriage 40 has been described as an example of the “signal output unit”. The “signal output unit” is not necessarily limited to such an encoder 90. That is, in the “signal output unit” here, any type of “signal output unit” may be used as long as a signal corresponding to the relative movement of the image reading sensor (image sensor 50) with respect to the document is output. It does not matter. That is, as long as the signal corresponds to the relative movement of the image reading sensor (image sensor 50) with respect to the document, the signals other than the pulse signals ENC-A and ENC-B having a period corresponding to the moving speed of the carriage 40 as described above. In addition, various types of signals such as a signal corresponding to the moving distance of the carriage 40 may be output.

<About timing signal>
In the above-described embodiment, the “timing signal” is described by taking, as an example, a signal that defines a reference timing for the lamp control unit 64 and the sensor control unit 66 to control the exposure lamp 46 or the image sensor 50. However, the “timing signal” herein is not necessarily limited to a signal that defines a reference timing for controlling the exposure lamp 46 or the image sensor 50 as described above. That is, other control units except the lamp control unit 64 and the sensor control unit 66 acquire data of an image read from the document 15 by the image reading sensor (image sensor 50) from the image reading sensor (image sensor 50). In addition, any signal may be used as long as it is a reference signal.

  Further, here, the “timing signal” corresponds to a reference timing for acquiring image data read from the document 15 by the image reading sensor (image sensor 50) from the image reading sensor (image sensor 50). However, the “timing signal” here is not necessarily limited to the signal having the pulse Wt. In other words, any type of signal may be used.

<About timing signal generation circuit>
In the above-described embodiment, a circuit that generates a timing signal based on the edges of the pulse signals ENC-A and ENC-B output from the encoder 90 has been described as the “timing signal generation circuit”. The “timing signal generation circuit” is not necessarily limited to such a circuit. That is, as long as a signal that defines a reference timing for acquiring data of an image read from the document 15 by the image reading sensor (image sensor 50) from the image reading sensor (image sensor 50) is generated. Such a type of “timing signal generation circuit” may be used.

<About the predetermined time>
In the above-described embodiment, as the “predetermined time”, the predetermined time Tm set as the mask period in the mask signal Sm output from the mask timer 114 is (A) the time Ts required for the charge transfer by the charge transfer unit 82. Longer than (B) the set time Tr of the exposure lamp 46, but in the “predetermined time” here, other than the requirements (A) and (B) It may be set according to other requirements. That is, the “predetermined time” may be any time as long as it is set in advance to a time that allows the image reading sensor to smoothly read the image from the document.

<About image reader>
In the above-described embodiment, the “image reading device” has been described by taking an example of an image reading device provided on a carriage in which an image reading sensor moves relative to a document set on a document table. The “image reading device” here is not necessarily limited to this type of “image reading device”. That is, any type of image reading apparatus may be used as long as the image reading apparatus includes an image reading sensor that moves relative to the document 15 and reads an image from the document. That is, the “image reading apparatus” here includes an image reading apparatus in which an original is moved relative to an “image reading sensor” and an image is read from the original.

1 is an explanatory diagram of an embodiment of an image reading system. FIG. FIG. 3 is an explanatory diagram illustrating an example of an internal configuration of an image reading apparatus. 1 is an explanatory diagram illustrating an example of a system configuration of an image reading apparatus. FIG. Explanatory drawing of an example of the light-emission method of an exposure lamp. Explanatory drawing of the transfer method of the electric charge which generate | occur | produced in the photoelectric conversion element. FIG. 6 is an explanatory diagram of an example of a timing signal output circuit. Explanatory drawing of the timing signal St output from a timing signal output circuit. 3 is an explanatory diagram illustrating an example of a configuration of a timing signal output circuit. FIG. Explanatory drawing of each signal produced | generated in a timing signal output circuit.

Explanation of symbols

10 image reading device, 12 document table, 14 document table cover, 15 document,
18 hinge part, 20 computer apparatus, 22 computer main body,
24 display device, 26 input device, 28 FD drive device,
30 CD-ROM drive, 32 reader, 34 keyboard,
36 mouse, 40 carriage, 42 drive mechanism, 44 guide, 46 exposure lamp,
48 lens, 50 image sensor, 52 control unit, 54 timing belt,
55 pulley, 56 pulley, 58 drive motor, 59 rotating shaft,
60 controller, 62 motor controller, 64 lamp controller,
66 sensor control unit, 68 AFE (Analog Front End) unit,
70 digital processing circuit, 72 interface circuit, 74 analog signal processing circuit,
76 A / D conversion circuit, 80 photodiode, 82 charge transfer unit, 84 gate,
90 encoder, 92 encoder code plate, 94 detector,
110 timing signal output circuit, 112 timing signal generation circuit,
114 mask timer, 116 mask circuit

Claims (9)

(A) an image reading sensor that moves relative to the document and reads an image from the document;
(B) a signal output unit that outputs a signal corresponding to a relative movement of the image reading sensor with respect to the document;
(C) A timing signal that defines a reference timing for acquiring data of the image read from the document by the image reading sensor from the image reading sensor based on the signal output from the signal output unit. A timing signal generator for generating
(D) When the timing defined by the timing signal generated by the timing signal generation unit is less than a predetermined time with respect to the previous timing, the image data from the image reading sensor A determination unit that determines that an error has occurred and acquisition has not been completed,
Equipped with a,
When the determination unit determines that the error has occurred, the image reading operation for reading an image from the document by the image reading sensor is stopped, and the image reading operation is resumed from a position before the error is determined. An image reading apparatus characterized by the above.   The image reading apparatus according to claim 1, wherein the signal output unit outputs a signal corresponding to a relative moving speed of the image reading sensor with respect to the document as the signal.   The image reading apparatus according to claim 1, wherein the signal output unit outputs a signal corresponding to a relative movement distance of the image reading sensor with respect to the document as the signal.   The image reading apparatus according to claim 1, wherein the signal output unit includes an encoder for outputting the signal. The image reading sensor reads the image by transferring charge from a photoelectric conversion element,
The image reading apparatus according to claim 1 , wherein the predetermined time is equal to or longer than a time required for transferring the electric charge . An exposure lamp that is lit when the image reading sensor reads the image;
5. The image according to claim 1, wherein the predetermined time is equal to or longer than an exposure time per cycle when a plurality of color lamps are individually turned on in the exposure lamp. Reading device.   The said determination part is provided with the timer which measures the elapsed time after the said timing prescribed | regulated by the said timing signal produced | generated by the said timing signal production | generation circuit generate | occur | produced. The image reading apparatus according to any one of the above.   The image according to any one of claims 1 to 7, wherein a target value of a relative movement speed of the image reading sensor with respect to the document is changed after the determination unit determines that the error has occurred. Reading device. (A) a step of moving an image reading sensor relative to an original to read an image from the original;
(B) outputting a signal corresponding to a relative movement of the image reading sensor with respect to the document;
(C) generating a timing signal that defines a reference timing for acquiring data of the image read from the document by the image reading sensor from the image reading sensor based on the output signal;
(D) The acquisition of the image data from the image reading sensor is not completed when the interval defined by the generated timing signal is less than a predetermined time with respect to the previous timing. And determining an error as
Have,
When the error is determined, the image reading operation for reading an image from the document by the image reading sensor is stopped, and the image reading operation is restarted from a position before the error is determined. Image reading method.