Image reading apparatus and method for reading a document during acceleration

Abstract: An image reading apparatus includes a reading device for reading a document to generate image data, and for outputting the image data at a predetermined cycle. A reading control unit receives the image data output by the reading device. A moving device, driven by a driving unit, moves the document and the reading device relative to each other. A timing control unit controls (i) a driving timing of the driving unit, and (ii) a data timing at which the image data output from the reading device is received by the reading control unit. The timing control unit controls the driving timing and the data timing such that a moving speed of the document is accelerated, and the image data output from the reading device is selectively received by the reading control unit in accordance with the driving timing.

Description: The present invention relates to an image reading apparatus having a reading means for reading the image of an original document. The present invention also relates to a corresponding image reading method. The document and the reading means are moved relative to each other by means of a stepping motor, and the image of the original document is read even while the stepping motor is being accelerated or decelerated. Generally, in a stepping motor, the pull-in torque thereof decreases with an increase in the rotational speed thereof. It is impossible to make a motor rotate suddenly at a speed exceeding the minimum self-start frequency. Therefore, when a motor is rotated where the pull-in torque is small or where the rotation speed exceeds the minimum self-start frequency, acceleration control must be performed so that the speed is gradually increased starting from a speed with a large pull-in torque. Hitherto, an image reading apparatus for reading the image of a document using a stepping motor by causing a document and reading means to move relative to each other and by controlling the acceleration of the stepping motor has been constructed as described below. The document is set in a document tray in an image reading apparatus in which a document is fed. The document begins to be fed from the set position, and acceleration control is terminated by the time the document reaches the position at which the image of the document is read. In an image reading apparatus featuring a moving-type optical system in which a document set in a document tray is read by moving the optical system, the optical system begins to move from the home position, and acceleration control is terminated by the time the document reaches the reading position in the document holder. However, in the related known prior art, when the reading operation is suspended due to a memory overflow or the like during the reading operation, the stopped position and hence, the reading position, is in the middle of the document. The related prior art has a problem in that if the reading operation is restarted from the position at which the reading is stopped, and if acceleration control for making the reading speed constant from the stopped state is performed, part of the image is skipped because no reading of the original document is performed during acceleration control. The torque of the stepping motor decreases with an increase in the rotational speed thereof. In the related prior art, since quick-acceleration control is performed in order to shorten acceleration time, the torque decreases considerably before the document reaches the reading position. As a result, in a document-feeding type image reading apparatus, an auto-document feeder (ADF) mechanism does not function satisfactorily, causing the following problems: (i) double-feeding of the documents, (ii) the motor is out of step when documents are fed which are stacked on one another in the feeding means and which have a large frictional resistance, or (iii) causing defective feeding. Document US-A-4 926 270 discloses a driving method for a stepping motor and a sheet conveying apparatus using the driving method. In particular, the pulse rate of a step motor is set dependent on the time detected between the generation of two sheet conveyance commands. Furthermore, a prior art arrangement is known from document EP-A-0 371 800. With the thus known apparatus, the timing at which the image data output from reading means is received by reading control means is controlled in accordance with an apparatus scanning period, as shown in Fig. 4B of this document. In particular, the image data output from the reading means is received by reading control means once at the beginning of each apparatus scanning period. Then, four motor driving pulses are output during each apparatus scanning period. Namely, according to this known prior art arrangement, due to the output of motor driving pulses and the timing at which the image data output from reading means is received by reading control means being controlled on the basis of the apparatus scanning period, it is impossible to perform control with high flexibility and a period occurs, in which period motor driving pulses are discontinuous. Hence, it is an object of the present invention to provide an improved image reading apparatus which is free from the above mentioned drawbacks. Furthermore, it is an object of the present invention to provide an improved image reading method which is free from such problems inherent to the prior art. A further aim of the present invention is to provide an image reading apparatus capable of reading a document by causing a document and reading means to move relative to each other even when the relative speed of the document and the reading means is being accelerated or decelerated. An other aim of the present invention is to provide an image reading apparatus in which high-speed reading is made possible even when reading has started in a condition in which the leading edge of the document has already passed the read position before acceleration is performed, that is, reading is possible from the middle of the document by reading the image even when the stepping motor, used for feeding a document in a document-feeding type image reading apparatus, is being accelerated. A still further aim of the present invention is to provide an image reading apparatus in which high-speed reading is possible even when it is started in a condition in which the optical system is stopped in the middle of the document, that is, even from the middle of the document, by reading the image even when the stepping motor, used for transporting the moving-type optical system, of an image reading apparatus is being accelerated. This object is achieved by an image reading apparatus according to claim 1. Moreover, this object is achieved by an image reading method as defined in claim 11. Advantageous further developments are as set out in the respective dependent claims. The above and further objects and aims and novel features of the invention will be more fully apparent from the following detailed description when read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only. Fig. 1 is a block diagram in accordance with an embodiment of the present invention; Fig. 2 is a timing chart for acceleration control and reading; Fig. 3(a) is a flowchart showing acceleration control and the reading operation; Fig. 3(b) shows an operation table; Fig. 4 schematically illustrates a passage through which a document is fed; Fig. 5(a) is a flowchart showing deceleration control and the reading operation; Fig. 5(b) shows an operation table; Fig. 6 shows an operation table for instructing deceleration control during memory overflow; and Fig. 7 is a schematic illustration of an image reading apparatus. An example of an application of the present invention to an image reading apparatus of a document-feeding type used in a facsimile or the like will be explained first. Fig. 1 is a block diagram for illustrating an image reading section in accordance with an embodiment of the present invention. In Fig. 1, reference numeral 1 denotes a control section; reference numeral 2 denotes a photoelectric conversion section for converting a read image into electrical signals; reference numeral 3 denotes a binarization section for converting electrical signals output from the photoelectric conversion section 2 into binary digital signals of white or black; reference numeral 4 denotes a serial/parallel conversion section for converting serial data output from the binarization section 3 into parallel data of a predetermined bit length which is convenient for the control section 1 to handle; reference numeral 5 denotes a clock generator for generating a data transfer clock for each pixel and a line synchronization signal for each line; reference numeral 6 denotes a storage section for storing read image data; reference numeral 7 denotes a motor driving section for driving a motor in accordance with an instruction from the control section 1; reference numeral 8 denotes a stepping motor for feeding a read document; reference numeral 9 denotes a data transfer clock signal; reference numeral 10 denotes a line synchronization signal; reference numeral 11 denotes a section for detecting the presence of a document; reference numeral 12 denotes an encoding and decoding section for encoding and decoding image data; reference numeral 13 denotes an encoding data storage section for storing encoded data; reference numeral 14 denotes a modem; and reference numeral 15 denotes a network control unit (NCU). An example will now be explained in which a document is read at the standard resolution mode of a facsimile apparatus by means of the reading apparatus of the facsimile in which a photoelectric conversion section is formed of a CCD (Charge Coupled Device) having a storage time of 2.5 ms, one line of the standard mode (3.851 line/mm) corresponding to 4 steps of a stepping motor for feeding. The line synchronization signal 10 is generated at a cycle which coincides with the storing operation of the CCD disposed in the photoelectric conversion section 2, and is input to the photoelectric conversion section 2 and the control section 1. A reading operation is performed with this signal as a reference. When the line synchronization signal 10 is input, the photoelectric conversion section 2 transfers the stored charge for each pixel into a shift register within the CCD, converts the charge into an electrical signal and transfers it into the binarization section 3 in synchronization with the data transfer clock signal 9. Data which is binarized by the binarization section 3 is transferred to the serial/parallel conversion section 4 in synchronization with the data transfer clock signal 9, where the data is converted into parallel data of a predetermined bit length (e.g., 8 bits) which is convenient for the control section to handle. These operations are repeatedly performed each time the line synchronization signal 10 is input. When the line synchronization signal 10 is input, the control section 1 (i) issues an instruction for stepping up the motor to the motor driving section 7 for stepping up the motor 8 in accordance with a predetermined timing, and (ii) reads one line of data from the serial/parallel conversion section 4 and transfers it to the storage section 6. Next, an explanation will be given of a method of reading an image at the standard mode while a motor is being accelerated in a system which is controlled with the line synchronization signal 10 as a reference. As an example, the number of rotations of the motor is accelerated from 800 pps to 1,600 pps. Fig. 2 illustrates the timing of sending instructions to the motor driving section 7 during acceleration control; stepping operations of the motor; and the timing at which image data is received from the CCD. In this embodiment, since the line synchronization signal 10, which is output at intervals of 2.5 m seconds, is used as a reference, the pulse rate of the stepping motor must be controlled on the basis of the cycle of the line synchronization signal 10. In this embodiment, the motor is smoothly accelerated by gradually increasing the pulse rate as shown in Fig. 2 from 4 steps (800 pps), to 5 steps (1,000 pps), 6 steps (1,200 pps), and 7 steps (1,400 pps), all of the foregoing being in 5 ms units, and from 4 steps (1,600 pps) in 2.5 ms units. The timing at which data is output from the CCD is important. Since the standard resolution is used, data must be received at a rate of one line for every 4 steps of the motor. Since, in practice, the data output timing of the CCD is at 2.5 ms intervals, and since 4 steps are scanned in 5 ms for 800 pps, data may be received from the CCD in accordance with a reading timing (output timing of the CCD) of once for every two pulses of the line synchronization signal 10. However, in 1,000 pps, 1,200 pps and 1,400 pps, the timing of the motor at 4 step intervals is out of phase with the output timing of the pulses of the line synchronization signal 10 (data output timing of the CCD). It is impossible to set the read timing at 4 step intervals in a condition in which the timing of the motor matches the output timing of pulses of the line synchronization signal 10 (data output timing of the CCD). Therefore, as shown in Fig. 2, the read timing is set so that data is received by the control section 1 at the timing at which data is output from the CCD, which timing is nearest to every 4 steps of the motor. Even with this setting, almost no distortion is seen in the read image. As a result, it is possible to read an image during acceleration. Based on the above, a document is fed by ADF to the read position at 800 pps. As shown in Fig. 2, if reading starts when the original document reaches position A and document feeding is accelerated from position B, it is possible to feed the document to the read position with a high torque. Therefore, an image reading section is realized in which the ADF has high separation and feeding capabilities. Since an acceleration pattern during acceleration control is greatly affected by the torque of the motor and the load of the mechanism, the acceleration pattern is not limited to that shown in Fig. 2. An explanation will now be given of an operation for receiving an instruction issued by the control section 1 to the motor driving section 7 and a read image with reference to Fig. 3 as regards the reading operation during acceleration control. Initially, when a document is fed and reaches the reading position as a result of an output from the section for detecting the presence of a document 11, the operation shown in the flowchart of Fig. 3(a) is initiated. Upon initiation of the reading operation, the control section 1 detects the line synchronization signal 10 input from the clock generator 5. When the first line synchronization signal is detected, the count value of a counter in the control section is set at 1 in step S100. Next, address 1 in the table shown in Fig. 3(b) is referred to in step S101. This table is made up of 8 bits: the first bit serves as a flag for indicating whether a read image signal output from the S/P conversion section 4 should be received; the second bit serves as a flag for indicating whether a control instruction should be issued to the motor driving section 7; the third to fifth bits serve as a code for indicating the pulse rate of the motor; and the sixth to eighth bits serve as a code for indicating the number of steps. Since address 1 indicates a read timing according to the content of the table, data output from the S/P conversion section 4 is received and an instruction for advancing 4 steps at 800 pps is given to the motor driving section 7. Since the count value is 1, for N > 1, in step S102, the process returns to step S100. When the second line synchronization signal is detected in step S100, the count value is set at 2. Then, the process proceeds to step S101 where the table in address 2 is referred to and, based on the table contents, no action is taken. Then, the process proceeds to step S102; since the count value is 2, for N > 2, in step S102, the process returns to step S100. When the third line synchronization signal is detected in step S100, data read from the table in address 3 is received in step S101, and, based on the table contents, an instruction for advancing 4 steps at 800 pps is given to the motor driving section 7. In this way, each time a line synchronization signal is detected in step S100, the operation table is referred to on the basis of the count value in step S101, and the operations referred to in the table are performed. When the count value reaches a value N at which the acceleration operation is to be terminated, the acceleration operation is terminated, and the operation shifts to a reading operation at a constant speed. Thereafter, because N = 17 in Fig. 3(b), the same operations as contained in address 17 are repeatedly performed until the end of the document is read. This table is stored in a memory within the control section 1. Therefore, the operation for acceleration control can be changed by changing the contents of this table. Next, a decelerated reading will be explained. When a plurality of document sheets are read in succession, decelerated reading is performed near the trailing edge of each document in order to make the next sheet synchronize with the feeding of the next document. Decelerated reading is also performed to suspend the reading operation when a memory overflow is likely to occur or to prevent the stepping motor from getting out of step. The process of reading a plurality of document sheets in succession will be explained first. Fig. 4 shows a schematic diagram of a reading and feeding passage. Reference numeral 20 denotes a reading glass window disposed at the reading position in the feeding passage; reference numerals 21a and 21b denote sensors for detecting the presence of a document; reference numerals 22a and 22b denote feeding rollers for feeding a document to the reading position; reference numeral 23 denotes a document separation member; reference numeral 24 denotes a document separation roller; reference numerals 25a and 25b denote ejection rollers for ejecting a document; reference numeral 26 denotes a document; reference numeral 27 denotes the next or succeeding documents; and reference numeral 28 denotes a stepping motor for driving rollers 22a, 24 and 25a. Assuming that the original document 26 is being read, the document separation roller 24 begins to rotate when the trailing edge of the original document 26 is detected by the sensors 21a and 21b. Turning on or off the document separation roller 24 is performed by a clutch mechanism or the like. The next document 27, separated by the document separation member 23, is guided to the feeding rollers 22a and 22b. After the leading edge of the next document 27 is detected by the sensors 21a and 21b, the accelerated reading operation described above is performed. Since the rollers 22a, 24 and 25a are driven by a single stepping motor, the rotational speed of each roller is synchronized with the number of rotations of the stepping motor. Therefore, if the leading edge of the next document 27 reaches the feeding rollers 22a and 22b during the time interval from when the trailing edge of the original document 26 being read passes through the sensors 21a and 21b to the time when the original document 26 passes the reading position, the next document 27 is fed at the speed at which the original document 26 is read. That is, if the original document 26 is read up to its trailing edge at a high speed (1,600 pps), the leading edge of the next document 27 reaches the feeding rollers 22a and 22b during that time, and is fed at a high speed (1,600 pp). Therefore, the next page is not fed at a low speed. To prevent high speed feeding, if the trailing edge of the original document 26 is detected passing through the sensors 21a and 21b, deceleration is started in preparation for feeding the next document 27, and the rest of the image of the original document 26 is read while being decelerated. Regarding decelerated control, the reverse of the above-described accelerated control is performed. Initially, when the trailing edge of the original document 26 is detected by the sensors 21a and 21b, the process shifts to the flowchart shown in Fig. 5(a), and the operations contained in the table in Fig. 5(b) are performed. In Figs. 5a and 5b, reading is decelerated at timings reverse to the operations shown in Figs. 3a and 3b. Next, decelerated reading when a memory overflow occurs will be explained. When image data is transmitted, an image read by the photoelectric conversion section 2 is stored in the storage section 6 via the binarization section 3 and the serial/parallel conversion section 4. Since the image data stored in the storage section 6 are image data for each pixel, they are encoded by the encoding and decoding section 12 and stored in the encoded data storage section 13. Thereafter, image data encoded again by the encoding and decoding section 12 in conformity with the encoding method of a corresponding station is read out from the encoded data storage section 13 and sent out from the NCU 15 to a public switched telephone network via the modem 14. Data for a plurality of sheets can be stored in the encoded data storage section 13. The stored data is read out from the storage section and transmitted. When the image of a document is transmitted, memory overflow may occur in the encoded data storage section 13 depending upon the type of document read or the number of sheets of the document. Therefore, the control section 1 monitors the free space capacity of the encoded data storage section 13. When the free space capacity of the memory falls below a predetermined amount, deceleration control during memory overflow is performed and the reading operation is stopped. This operation is the same as when the trailing edge of the document is detected, as described above, except that a different table is referred to. Initially, in Fig. 5(a), N is set at 7, and reference to the table of Fig. 6 is initiated. At this time, the degree of deceleration is high. However, there is no inconvenience caused, for instance, when the motor suddenly stops without having performed deceleration control. The reason why the motor stops quickly in accordance with the deceleration operation at a memory overflow time shown in Fig. 6 is to save the free space capacity of the memory. That is, if the number of lines to be read until the motor stops is great, a large amount of the free space capacity of the memory is required to store the encoded image data which has been read during that time. This is inefficient. Since the amount of the free space capacity of the memory monitored by the control section 1 is determined in accordance with an image pattern such that the maximum number of bits is required after encoding one line of image data in conformity with the encoding method used, if the number of lines to be read from the point of deceleration until stoppage is great, a considerable amount of free space capacity is required. This is inefficient. Therefore, the deceleration operation during memory overflow is performed to quickly decelerate and stop the motor. Next, when reading is restarted, the reading may be performed in such a way that it is reaccelerated while monitoring the free space of the encoded data or in such a way that the reading is performed line by line at a low speed and starting and stopping of reading of one line may be repeated at a low speed. Further, even when reading from the middle of the document, the image of the document is read while performing acceleration control. As described above, since the image may be read while acceleration is being performed, high-speed reading is possible even from the middle of the document. In addition, since an image may be read while acceleration or deceleration is being performed, even when an image is to be transmitted from the middle of the document or when the reading operation is stopped during the reading due to a memory overflow or the like, it is possible to read a well-linked image without image data being lost. In addition, since the document is fed at a high speed up to the reading position and acceleration is started when the document has reached the reading position, the document separation and feeding capabilities of an ADF can be improved. Next, the application of the present invention to the optical-system-type image reading apparatus will be explained with reference to a preferred embodiment. Fig. 7 is a schematic illustration of an image reading apparatus. Reference numeral 401 denotes a glass document holder; reference numeral 402 denotes a bar-shaped light source, such as a halogen or fluorescent lamp; reference numeral 403 denotes a first mirror; reference numeral 404 denotes a second mirror; reference numeral 405 denotes a third mirror; reference numeral 406 denotes a lens; reference numeral 407 denotes a one-dimensional solid-state imaging element (image sensor), such as a CCD line sensor; and reference numeral 408 denotes a white reference surface for correcting the shading. The operation of a document reading apparatus will be explained. A document placed on the glass document holder 401 is illuminated by the bar-shaped light source 402. The document is formed into an image on the image sensor 407 through the first mirror 403, the second mirror 404 and the third mirror 405 which scan (sub-scan) the document. The main scanning direction of the image sensor 407 is perpendicular to the figure plane. The bar-shaped light source 402 and the first mirror 403 are formed integrally by means of a support (not shown), and scan the surface of the document while moving in the F direction in the figure, guided by a guide rail (not shown). The second mirror 404 and the third mirror 405 are formed integrally by means of a support (not shown), and moved along a guide rail (not shown) at a speed one half of the speed of the first mirror 403 and in the same direction as the first mirror 403. The bar-shaped light source 402, the first mirror 403, the second mirror 404 and the third mirror 405 move to the positions 402', 403', 404' and 405', respectively, indicated by the dotted lines in the figure. At this time, the optical path from the document holder 401 to the lens 406 through the mirrors 403, 404 and 405 is maintained at a constant length. The above movements are performed by supplying driving signals to the pulse motor (not shown). Therefore, if, during sub-scanning, signals from a photoreceptor element of the image sensor 407 are read out in the right order, sequential signals by raster scanning the surface of the document can be obtained. In the reading position in Fig. 7, the white reference surface for correcting the shading is positioned at the home position. When the document on the glass document holder 401 is read, the bar-shaped light source 402 at the home position and the mirrors 403, 404 and 405 are moved by a pulse motor. At this time, the image sensor 407 and the pulse motor are driven under the control described in connection with Figs. 2 and 3. At this time, the read start position (point X) on the document holder in Fig. 7 corresponds to point A in Fig. 2. Therefore, the optical system which begins to move from the home position is driven at 800 pps. After the optical system reaches point X in Fig. 7 (point A in Fig. 2), reading is started under the control described in connection with Fig. 3. Further, the moving optical system may be accelerated from the home position so that read data may be taken in from the position where the moving optical system has reached point X in Fig. 7. Next, the suspension of reading will be explained. This is the same as the operation of the reading apparatus of the document feeding type. Reading is suspended under the control, described in connection with Fig. 6, of an unillustrated control section. A deceleration operation can also be performed if necessary. This operation is performed under the control described in connection with Fig. 5. The individual components shown in outline or designated by blocks in the Drawings are all well known in the image reading arts and their specific construction and operation are not critical to carrying out the operation or best mode for carrying out the invention. An image reading apparatus includes a reading device for reading a document to generate image data, and for outputting the image data at a predetermined cycle. A reading control unit receives the image data output by the reading device. A moving device, driven by a driving unit, moves the document and the reading device relative to each other. A timing control unit controls (i) a driving timing of the driving unit, and (ii) a data timing at which the image data output from the reading device is received by the reading control unit. The timing control unit controls the driving timing and the data timing such that a moving speed of the document is accelerated, and the image data output from the reading device is selectively received by the reading control unit in accordance with the driving timing.

Claims: An image reading apparatus, comprising: reading means ( 2 ) for reading a document to generate image data, and for outputting the image data at a predetermined cycle ( 10 ); reading control means ( 3, 4 ) for receiving the image data output by said reading means; moving means ( 8 ) for moving the document and said reading means relative to each other; driving means ( 7 ) for driving said moving means; timing control means ( 1, 5, 9, 10 ) for controlling (i) a driving timing of said driving means, and (ii) a timing at which the image data output from said reading means is received by said reading control means; wherein said timing control means ( 1, 5, 9, 10 ) controls (i) the driving timing such that said driving means continuously outputs pulses such that a moving speed of the document relative to said reading means is accelerated or decelerated, and (ii) the data timing such that desired one of the image data output from said reading means, during the acceleration period or deceleration period, is selectively received by said reading control means, and a memory, wherein the driving timing of said driving means are stored in the memory as a preset control table characterized in that said memory also stores the data timing at which said reading control means receives the image data output from said reading means as a preset control table, and said timing control means reads out the data timing from the memory in accordance with the predetermined cycle ( 10 ) and controls (i) the driving timing such that said driving means continuously outputs pulses such that a moving speed of the document relative to said reading means is accelerated or decelerated, and (ii) the data timing such that desired one of the image data output from said reading means, during the acceleration period or deceleration period, is selectively received by said reading control means. An image reading apparatus according to claim 1, characterized in that said moving means includes a pulse motor. An image reading apparatus according to claim 2, characterized in that said driving means outputs a plurality of driving pulses for said pulse motor, and controls a driving pulse output timing. An image reading apparatus according to claim 3, characterized in that said driving means controls a pulse rate of the plurality of driving pulses. An image reading apparatus according to claim 4, characterized in that said timing control means performs control such that the image data output from said reading means is received by said reading control means at intervals of a predetermined number of driving pulses. An image reading apparatus according to claim 5, characterized in that said timing control means performs control such that the image data output from said reading means is received by said reading control means, the image data being output at a timing nearest to the driving pulse output timing at the intervals of the predetermined number of driving pulses. An image reading apparatus according to claim 1, characterized in that said moving means includes feeding means for feeding the document. An image reading apparatus according to claim 7, characterized in that said moving means further includes detecting means for detecting a position of the document. An image reading apparatus according to claim 8, characterized in that said timing control means starts acceleration control and/or deceleration control after a leading edge of the document has reached a reading position at which the document is read by said reading means in response to an output from said detecting means. An image reading apparatus according to claim 1, characterized by a document holder in which the document is set, and a moving optical system for scanning the document in said document holder and for guiding image data to said reading means, wherein said moving means moves said moving optical system. An image reading method, comprising the steps of: reading a document to generate image data using a reading means ( 2 ), and outputting the image data at a predetermined cycle ( 10 ); receiving the image data obtained by reading using a reading control means ( 3, 4 ); moving the document and said reading means relative to each other using a moving means ( 8 ); driving said moving means using a driving means ( 7 ); controlling using a timing control means ( 1, 5, 9, 10 ) (i) a driving timing of said driving means, and (ii) a timing at which the image data obtained by reading is received by said reading control means; wherein said controlling is effected on (i) the driving timing such that said driving means continuously outputs pulses such that a moving speed of the document relative to said reading means is accelerated or decelerated, and on (ii) the data timing such that desired one of the image data obtained by reading, during the acceleration period or deceleration period, is selectively received by said reading control means, and wherein the driving timing of said driving means are stored in a memory as a preset control table characterized in that also the data timing at which said reading control means receives the image data output from said reading means are stored as a preset control table in said memory, and reading out the data timing from the memory in accordance with the predetermined cycle ( 10 ) is effected using said timing control means and control is effected using said timing control means on (i) the driving timing such that said driving means continuously outputs pulses such that a moving speed of the document relative to said reading means is accelerated or decelerated, and on (ii) the data timing such that desired one of the image data output from said reading means, during the acceleration period or deceleration period, is selectively received by said reading control means. An image reading method according to claim 11, characterized in that moving is effected using a pulse motor. An image reading method according to claim 12, characterized by outputting a plurality of driving pulses for said pulse motor, and controlling a driving pulse output timing, using said driving means. An image reading method according to claim 13, characterized by controlling a pulse rate of the plurality of driving pulses using said driving means. An image reading method according to claim 14, characterized by performing control using said timing control means such that the image data output from said reading means is received by said reading control means at intervals of a predetermined number of driving pulses. An image reading method according to claim 15, characterized by performing control using said timing control means such that the image data output from said reading means is received by said reading control means, the image data being output at a timing nearest to the driving pulse output timing at the intervals of the predetermined number of driving pulses. An image reading method according to claim 11, characterized by feeding the document using feeding means included in said moving means. An image reading method according to claim 17, characterized by detecting a position of the document using detecting means further included in said moving means. An image reading method according to claim 18, characterized by starting acceleration control and/or deceleration control after a leading edge of the document has reached a reading position at which the document is read by said reading means in response to an output from said detecting means, using said timing control means. An image reading method according to claim 11, characterized by setting a document in a document holder, and scanning the document in said document holder and guiding image data to said reading means using a moving optical system, wherein said moving optical system is moved by said moving means. An image reading apparatus according to claim 1, wherein the driving timing and the data timing are stored in the same control table. An image reading method according to claim 11, wherein the driving timing and the data timing are stored in the same control table. An image reading apparatus according to claim 1, wherein said control means is a control section (1). An image reading method according to claim 11, wherein said control means is a control section (1).

Inventors: ONO TAKASHI, ONO, TAKASHI, ONO, TAKASHI, C/O CANON KABUSHIKI KAISHA
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1993
Main classification: H04N1
IPC codes: H04N1, H02P8