JP5313723B2 - Image reading device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reader capable of reducing power consumption in an intermittent drive mode of shifting to a read interruption state of tentatively interrupting the conveyance of an original and image read in the middle of reading images from the original being conveyed. <P>SOLUTION: The image reader executes the control of shifting to the read interruption state of tentatively interrupting the conveyance of the original and the image read in the middle of reading the images from the original being conveyed, the control of stopping supply of driving signals to at least one of an image read sensor, an analog signal amplification part and a signal conversion part in the read interruption state, and the control of recovering from the read interruption state in order to restart the image read. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an image reading apparatus that reads an original image in an image scanner, a facsimile apparatus, and the like, and a control method therefor, and more particularly, to illuminate an original with a light source using an LED and to display a line image of the original in a CIS (Contact Image Sensor) ) It is suitable for use in an image reading apparatus configured to sequentially capture images with a one-dimensional image sensor such as a sensor.

  In the conventional image reading apparatus, when the free space of the buffer memory becomes small during image reading or the host PC becomes busy, the image data cannot be temporarily stored or delivered. In addition, there is an intermittent reading mode that shifts to a reading interruption state in which the document conveying operation is temporarily interrupted and waits until these states are recovered by the progress of transmission of image data to the external apparatus.

If the document is stopped during image reading and the conveyance of the document is stopped, the image data read while the document is stopped becomes meaningless data. Therefore, the image data is not output to an external device such as a host PC. Processing such as throwing away inside the reader. Further, since the image data read during the stop is discarded as described above, the document does not need to be irradiated with light, and there is no problem even if the light source is not turned on. For this reason, there has been proposed an image reading apparatus configured to turn off the light source while stopping the conveyance of the document in the intermittent reading mode so as not to waste electricity.
Japanese Patent Laid-Open No. 10-23219

However, in the above prior art, although the light source is turned off when the conveyance of the document is stopped, the image processing is also performed when the conveyance of the document is stopped in order to avoid the unstable operation of the processing circuit that is supposed to be an adverse effect of the intermittent reading operation. Control signals are supplied to a sensor, an operational amplifier, an A / D converter, or an AFE (Analog Front End IC) in the same manner as in a normal reading operation to operate them. For this reason, even when the conveyance of the original is stopped in the intermittent reading mode, the LED is turned off, and power that is almost the same as that in the normal reading is consumed.

An object of the present invention is to provide an image reading apparatus that can further reduce power consumption.

In order to achieve the above object, an image reading apparatus of the present invention includes a light source that irradiates light on a document, an image reading sensor that receives reflected light from the document and converts it into an analog image signal, and amplifies the analog image signal. An analog signal amplifying unit, a signal converting unit that converts the amplified analog image signal into a digital signal, a conveying unit that conveys an original, and conveyance and image reading of an original during image reading from the original being conveyed Control means for performing control for shifting to a reading interruption state that is temporarily interrupted, control for returning from the reading interruption state in order to resume image reading, and control relating to transmission of image data read from a document being conveyed to an external device And when the control means shifts to the reading interruption state during execution of control related to transmission of image data to the external device, The drive signal for the image reading sensor is set in a supply stop state, and at least one of the power supply and the drive signal for at least one of the analog signal amplification unit and the signal conversion unit is set in a supply stop state. When returning from the suspended state, the image reading sensor is provided with a sensor resumption drive unit that supplies a predetermined number of drive signals to the image reading sensor, and the sensor resumption drive unit outputs a drive signal for the predetermined number of times to the image reading sensor. After the supply, the control means controls the at least one of the analog signal amplification unit and the signal conversion unit to return from the supply stop state .

According to the present invention, it is possible to provide an image reading apparatus with reduced power consumption during intermittent reading operation.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a diagram illustrating the configuration of an image reading apparatus to which the present invention is applied. The outline of the image reading apparatus will be described below. The configuration of the image reading apparatus shown in FIG. 2 is schematic and is not limited to this configuration.

2, 100 is an image reading apparatus, 100A is an image reading apparatus main body, 100B is a sheet stacking section that is a sheet storing section for stacking and storing sheets S, and 103 is a line sensor that receives reflected light from the sheet S and reads an image. In this embodiment, the CIS sensor is a contact image sensor.

Here, the line sensor 103 will be described with reference to FIG. In FIG. 3, 301 is a light guide for diffusing the light of the LED 304 as a light source, 302 is also a light guide for diffusing the light of the LED 305, 303 is light reflected from the document, and CIS. It is a rod lens array for guiding to a sensor element. Although not shown in the figure, a CIS sensor element substrate is installed in the back of the rod lens array 303. The LEDs 304 and 305 are red, green, and blue LEDs, and are connected to a drive circuit (not shown).

Returning to FIG. A sheet feeding device 100 </ b> C feeds the sheet S stored in the sheet stacking unit 100 </ b> B to the line sensor 103. The sheet feeding roller 1 serving as a feeding rotating body and the separating roller 2 serving as a separating rotating body pressed against the feeding roller 1 are separated to separate the sheets S stacked on the sheet stacking unit 100B one by one. The sheet feeder 100C includes a feeding unit. Reference numeral 3 denotes a feed motor for driving the feed roller 1, the separation roller 2, and the like. The rotation of the feed motor 3 is also transmitted to the transport rollers 102a and 105, the platen roller 103a, and the paper discharge rollers 104 and 104b by a drive gear (not shown).

FIG. 5 is a diagram for explaining how the driving force is transmitted to the conveying unit as the separation feeding unit. In FIG. 5, 34 is a gear group for transmitting the driving force of the main motor 3 in FIG. 1, and 25 is connected to the gear group 34 and is connected to the feed roller shaft 5 a via the one-way clutch 28 to drive the feed roller 1. It is the drive gear for doing. Further, the rotational force of the drive gear 25 is transmitted to the shaft 6a by the drive gear 27 fixed to the gear 26 and the shaft 6a of the separation roller 2. As a result, the separation roller 2 rotates through the torque limiter 31 mounted inside the separation roller 2.

The feed roller 1 rotates in the sheet conveying direction, and the separation roller 2 is formed of an elastic body, and power is transmitted so as to rotate in a direction to return the sheet in the direction opposite to the sheet conveying direction. In addition, the torque limiter 31 is provided in the drive transmission path of the separation roller 2 and the sheet is conveyed in a state where there is no sheet S or when one sheet is conveyed between the feed roller 1 and the separation roller 2. Rotate following the direction. In a state where a plurality of stacked sheets S enter between these rollers, the separation roller 2 is configured to rotate in the direction opposite to the sheet conveying direction, and the sheets S can be separated and conveyed one by one.

FIG. 1 is a block diagram showing an outline of the circuit configuration of the image reading apparatus according to the first embodiment of the present invention. Hereinafter, FIG. 1 will be described. Reference numeral 11 denotes a CIS sensor (image reading sensor) that converts reflected light from an original into an electrical signal, accumulates it, and outputs an analog signal. Photoelectric conversion elements are arranged in a line. When the line head signal is input, the CIS sensor 11 photoelectrically converts the light irradiated by the light source 15 and reflected by a document being conveyed (not shown), and accumulates charges. Thereafter, the accumulated charge is converted into an output signal and output to the next stage circuit as an analog signal (analog image signal) in accordance with the drive clock.

Next, the amplifier circuit (analog signal amplifier) 12 amplifies the analog signal output from the CIS sensor 11. The amplifying circuit 12 can amplify the analog signal to a desired value by reducing noise by sampling or the like synchronized with the drive clock, or by adjusting the gain by an external instruction such as a gain switching signal. Reference numeral 13 denotes an A / D converter (signal converter) which converts the analog signal amplified by the amplifier circuit 12 into a digital signal having a designated bit width and outputs it in accordance with the drive clock. The A / D converter 13 samples an analog signal in accordance with the sample timing signal. The amplifier circuit 12 and the A / D converter 13 may be realized by one IC by using AFE (Analog Front End IC).

The reading operation control unit 14 supplies drive signals to each circuit, light source lighting timing control, and supply of drive control signals to the drive control unit. A light source 15 corresponds to the LEDs 304 and 305 shown in FIG. Reference numeral 16 denotes a light source lighting unit for lighting the light source 15, and is constituted by a constant current circuit or the like. The light source lighting unit 16 lights the light source 15 in accordance with the light source lighting signal from the reading operation control unit 14. The light source 15 includes red, green, and blue LEDs as described with reference to FIG. 3, and the reading operation control unit 14 and the light source lighting unit 16 are configured so that each LED can be individually lit.

The feed motor 17 corresponds to the feed motor 3 in FIG. The feed motor 17 is driven by the drive control unit 18. The drive control unit 18 controls rotation, stop, speed, and the like of the feed motor 17 according to an instruction of a drive control signal from the reading operation control unit.

The buffer memory 19 temporarily stores the image data generated by digital conversion in the A / D conversion unit and then input to the reading operation control unit 14. An external I / F unit 20 sends the image data stored in the buffer memory 19 to a host PC (not shown) connected to the image reading apparatus via the reading operation control unit 14.

FIG. 4 is a flowchart showing the operation of the image reading apparatus in this embodiment. When the start of scanning is instructed from the connected host PC or the like, the reading operation control unit 14 drives the CIS sensor 11 to drive clock and line head signal, the amplifier circuit 12 to drive clock, the A / D converter 13 to sample timing signal, A control signal such as a drive clock is output (step S401). The CIS sensor 11 starts scanning upon input of the drive clock and the line head signal, but since the document has not yet reached the reading start position at this time, the image data output at this time is unnecessary. Therefore, the reading operation control unit 14 does not capture this image data. Next, when the drive control unit 18 is instructed to start driving, the drive control unit drives the feed motor 17 and conveys the document (step S402). If the initial position of the document to be transported is different from the reading start position, driving of the feed motor is started first, and the start of control signal output may be delayed until the document arrives just before the reading start position. It doesn't matter. Further, the light source lighting signal may be output from the time when the document reaches the reading start position.

When the document reaches the reading start position (step S403), in order to start capturing the image data, first, it is confirmed whether there is enough space in the buffer memory 19 to capture the image data (S404). If there is sufficient free space in the buffer memory, the image data is fetched line by line and transferred to the host PC (steps S405 and S406). Note that the transfer of image data is described as a synchronous transfer in step S406 as an example, but it is also possible to transfer the image data asynchronously. If the host PC cannot be transferred due to the busy state or the like, the image data is not transferred in step S406. The operations in steps S404 to S406 are repeated until reading and transfer of one page of the document are completed.

If it is determined in step S404 that there is not enough free space in the buffer memory due to delay in taking image data at the host PC, etc., the control on the transmission of the image data to the host PC continues to be executed. Cannot be taken into the buffer memory 19, so that the feed motor is stopped to temporarily interrupt the reading operation during reading (step S410). At this time, the reading operation control unit 14 stops outputting signals related to the execution of the reading operation, such as stopping the control signal supplied to the CIS sensor 11 amplification circuit 12, the A / D conversion unit 13, and the light source lighting unit 19. (Processing for stopping supply) is performed (step S411). With this configuration, when the reading operation is stopped, the CIS sensor 11, the amplifier circuit 12, the A / D conversion unit 13, and the light source lighting unit 19 do not operate, and wasteful power can be reduced. If each unit has a function that can reduce the amount of power used, such as a sleep function, the power can be saved by using this function instead of stopping the control signal. In addition, any two or one of the control signals supplied to the CIS sensor 11 amplification circuit 12, the A / D conversion unit 13, and the light source lighting unit 19 may be stopped. Is possible.

When the transfer of the image data to the host PC proceeding in parallel proceeds and the buffer memory 19 has a sufficient free space (Yes in step S412), the reading operation control unit 14 again performs the CIS sensor 11 and the amplification circuit. 12, the control signal is supplied to the A / D conversion unit 13 and the light source lighting unit 19 (step S413). In this way, the CIS sensor 11, the amplifier circuit 12, the A / D conversion unit 13, and the light source lighting unit 19 are started to operate, and the drive control unit 18 is instructed to start driving. The drive control unit controls the feed motor 17. Driven and resumes document conveyance (step S414). If it takes time for the CIS sensor 11, the amplifier circuit 12, the A / D converter 13 and the like to operate stably, the process may wait for that time before executing step S414.

When the above procedure is repeated and image data for one page of the original is read (Yes in step S407), the motor drive and control signals are stopped (steps S408 and S409), and the scanning operation for one page is completed. . In the configuration of this embodiment, there is no free space in the buffer memory 19, image data is transferred to the host PC, the scan operation is stopped and the control signal to each device is stopped for the time until the free space increases. By stopping the operation of the device, it is possible to reduce the power consumption during this waiting time. Note that when a plurality of documents are continuously read, the above scanning operation is repeated.

The second embodiment of the present invention will be described below with reference to the drawings. First, FIG. 6 is a flowchart illustrating the operation of the image reading apparatus to which the present invention is applied. The outline of the image reading apparatus will be described below. The configuration of the main body and the circuit configuration are the same as those shown in FIGS. 1, 2, 3, and 5 shown in the first embodiment. However, the CIS sensor used in this embodiment returns when the operation is temporarily stopped. The difference is that it requires action. The necessity of this return operation will be described. While the drive clock and line head signal supplied to the CIS sensor are stopped, the light source is not turned on. In the state where the light source is not turned on, the CIS sensor should originally not accumulate charges, but the CIS sensor gradually accumulates charges due to the influence of external light or leakage current. If the state in which the charge is accumulated in this way continues for a long time, the charge is saturated and the CIS sensor may not operate normally. In order to recover to the normal operation state once such a state is reached, it is necessary to perform a reset process in which the line head signal is input several times while the drive clock is supplied and the charge of the CIS sensor is discharged. is there.

In FIG. 6, when the start of scanning is instructed from a connected host PC or the like, the reading operation control unit 14 outputs a drive clock and a line head signal to the CIS sensor 11 (step S601). By supplying a driving clock and a line head signal to the CIS sensor 11, dummy reading of a plurality of lines is performed. The CIS sensor 11 starts accumulating charges in accordance with the supply of the line head signal and continues accumulating for a predetermined time, and then outputs the accumulated charges in accordance with the drive clock. By repeating this several times, unnecessary charges accumulated in the CIS sensor 11 when the operation is stopped are swept out and reset to recover to a normal operation state.

The number of dummy readings (predetermined number of readings) for performing the recovery operation described above. By observing the output waveform from the CIS sensor 11 in advance, how many dummy readings can be performed before recovery. It is possible to determine in advance how many line head signals are appropriate. The dummy reading is repeated for the number of times until the line head signal is output, and the recovery operation is performed (step S602). After the recovery operation is completed, a drive signal is supplied to the amplifier circuit 12, the A / D converter 13 and the like (step S603).

By inputting drive signals to the CIS sensor 11, the amplifier circuit 12, and the A / D converter 13, image data can be input to the reading operation controller 14. At this point, the document is still at the reading start position. Since it has not reached, the image data output at this point is unnecessary, and the reading operation control unit 14 does not capture this image data. Alternatively, the image data may be captured and discarded. Next, when the drive control unit 18 is instructed to start driving, the drive control unit drives the feed motor 17 and conveys the document (step S604). The light source lighting signal may be supplied from the time of step S603, but image data until the original reaches the reading start position is unnecessary, and thus the light source lighting signal is supplied after the original reaches the reading start position. You may comprise so that it may do.

When the document reaches the reading start position (step S605), in order to start capturing image data, first, it is confirmed whether or not there is enough space in the buffer memory 19 to capture image data (step S606). If there is sufficient free space in the buffer memory, the image data is fetched line by line and transferred to the host PC (steps S607 and S608). Note that the transfer of image data is described as a synchronous transfer in step S608 as an example. However, if the host PC can accept other than that, the image data transfer is performed asynchronously with respect to the image reading operation. To do. If the host PC is not acceptable due to a busy state or the like, the image data is not transferred in step S608. The operations from step S606 to S608 are repeated for one page of the document. If it is determined in step S606 that there is not enough free space in the buffer memory due to a delay in taking image data on the host PC side, the image data cannot be taken in, and the feed motor is driven to temporarily stop the reading operation. Is stopped (step S612). At this time, the reading operation control unit 14 is related to performing the reading operation such as stopping (blocking) the control signal supplied to the CIS sensor 11, the amplifier circuit 12, the A / D conversion unit 13, and the light source lighting unit 19. The output of the signal is stopped (processing for setting the supply stop state) (step S613). With this configuration, when the reading operation is stopped, the CIS sensor 11, the amplifier circuit 12, the A / D conversion unit 13, and the light source lighting unit 19 do not operate, and wasteful power consumption can be suppressed. Note that two or one (that is, at least one) control signal of the amplifier circuit 12, the A / D conversion unit 13, and the light source lighting unit 19 may be stopped, and a certain amount of power consumption can be reduced. .

When the transfer of image data to the host PC proceeding in parallel advances and a sufficient free space is made in the buffer memory 19 (Yes in step S614), first, a drive clock and a line head signal are sent to the CIS sensor 11 in advance. The number of times is supplied (step S615). By doing so, similarly to step S601, a reset process for sweeping out the charges accumulated in the CIS sensor 11 when the operation is stopped is performed, and the normal operation state is recovered. After performing the recovery operation a predetermined number of times (step S616), the reading operation control unit 14 supplies control signals to the amplifier circuit 12, the A / D conversion unit 13, and the light source lighting unit 19 (step S617). When only one of the amplifier circuit 12 and the A / D conversion unit 13 has cut off the supply of the control signal, the supply of the control signal to one of the two is resumed. In other words, including other cases, the supply of the control signal to at least one of the two is resumed. In this way, the CIS sensor 11, the amplifier circuit 12, the A / D conversion unit 13, and the light source lighting unit 19 are started to operate, and the drive control unit 18 is instructed to start driving. The drive control unit controls the feed motor 17. Driven and resumes document conveyance (step S618).

When the above procedure is repeated and the image data for one page of the original is read (Yes in step S609), the driving of the feed motor and the transmission of the control signal are stopped (steps S610 and S611). Ends. In the configuration of the present embodiment, the buffer memory 19 runs out of free space, the image data is transferred to the host PC, the scan operation is stopped for the time until the free space increases, and the control signal to each device is stopped. By stopping the operation of each device, it is possible to reduce the power consumption during this waiting time. In addition, the dummy driving of the CIS sensor 11 is executed a predetermined number of times before starting or restarting the document reading, so that charges accumulated in the CIS sensor 11 while the reading operation is stopped are swept out to operate normally. Is possible. Note that when a plurality of documents are continuously read, the above scanning operation is repeated.

A third embodiment of the present invention will be described below with reference to the drawings. First, FIG. 7 is a block diagram showing an outline of a circuit configuration of an image reading apparatus according to the third embodiment of the present invention. The outline of the image reading apparatus will be described below. The mechanical structure of the main body is the same as that shown in FIGS. 2, 3, and 5 shown in the first embodiment. FIG. 7 will be described. The circuit configuration of FIG. 7 is a configuration in which a power supply control unit 711 for controlling power on / off of each block is added to the circuit configuration of FIG.

The CIS sensor 701 reads an image and outputs an analog signal, and photoelectric conversion elements are arranged in a line. When a line head signal is input, the CIS sensor 701 photoelectrically converts light reflected from a document (not shown) irradiated by the light source 705 and accumulates charges. Thereafter, the accumulated electric charge is converted into an output signal, which is output to the next stage circuit as an analog signal in accordance with the drive clock. An amplification circuit 702 amplifies an analog signal output from the CIS sensor 701. The amplifier circuit 702 can amplify the analog signal to a desired value by reducing noise by sampling or the like synchronized with the drive clock, or by adjusting the gain in response to an external instruction such as a gain switching signal. Reference numeral 703 denotes an A / D converter that converts the analog signal amplified by the amplifier circuit 702 into a digital signal having a designated bit width and outputs it in accordance with the drive clock. The A / D conversion unit 703 samples an analog signal in accordance with the sample timing signal. The amplification circuit 702 and the A / D conversion unit 13 may be realized by one IC by using AFE (Analog Front End IC).

  The reading operation control unit 704 supplies drive signals to each circuit, light source lighting timing control, supply of drive control signals to the drive control unit, and the like. A light source 705 corresponds to the LEDs 304 and 305 shown in FIG. Reference numeral 706 denotes a light source lighting unit for turning on the light source 705, which includes a constant current circuit. The light source lighting unit 706 turns on the light source 705 in accordance with the light source lighting signal from the reading operation control unit 704. The light source 705 includes red, green, and blue LEDs as described with reference to FIG. 3, and the reading operation control unit 704 and the light source lighting unit 706 are configured so that each LED can be individually lit.

  The feed motor 707 corresponds to the feed motor 3 in FIG. The feed motor 707 is driven by the drive control unit 708. The drive control unit 18 controls rotation, stop, speed, and the like of the feed motor 707 according to an instruction of a drive control signal from the reading operation control unit. A buffer memory 709 temporarily stores image data generated by the A / D conversion unit 703 and input to the reading operation control unit 704. The external I / F unit 710 sends the image data stored in the buffer memory 709 to a host PC (not shown) connected to the image reading apparatus via the reading operation control unit 704. Reference numeral 711 denotes a power control unit which can independently turn on / off the power supplied to the CIS sensor 701, the amplifier circuit 702, the A / D conversion unit 703, and the light source lighting unit 706.

Next, the operation of the image reading apparatus will be described using the flowchart of FIG. When the start of scanning is instructed from a connected host PC or the like, the reading operation control unit 704 outputs a driving clock and line head signal to the CIS sensor 701, a driving clock to the amplification circuit 702, a sample timing signal to the A / D conversion unit 703, A control signal such as a drive clock is output (step S801). The CIS sensor 701 starts scanning by inputting a drive clock and a line head signal, but since the document has not yet reached the reading start position at this point, the image data output at this point is meaningless. Since it is data, the reading operation control unit 704 does not capture this image data. Next, when an instruction to start driving is given to the drive control unit 708, the drive control unit drives the feed motor 707 and conveys the document (step S802). If the initial position of the document to be transported is different from the reading start position, the motor is started first, and the output of the control signal is delayed until the document reaches a predetermined position before the reading start position. It doesn't matter. The light source start signal may be output from the reading start position.

When the document reaches the reading start position (Yes in step S803), in order to start capturing image data, first, it is confirmed whether there is enough space in the buffer memory 709 to capture image data (step S804). If there is sufficient free space in the buffer memory, image data is fetched line by line and transferred to the host PC (steps S805 and S806). Note that the transfer of image data is described as a synchronous transfer in step S806 as an example. However, if the host PC can accept other than that, the transfer is performed asynchronously with respect to the image reading operation. If the host PC is not acceptable due to the busy state or the like, the image data is not transferred in step S806. The operations in steps S804 to S806 are repeated until reading and transfer of one page of the document are completed. If it is determined in step S804 that there is not enough free space in the buffer memory due to a delay in taking the image data at the host PC, the image data cannot be taken in, and the feed motor is driven to temporarily stop the reading operation. Is stopped (step S810). At this time, the reading operation control unit 704 outputs a signal related to the execution of the reading operation such as stopping the control signal supplied to the CIS sensor 701, the amplifier circuit 702, the A / D conversion unit 703, and the light source lighting unit 709. Stop (processing to stop supply) is performed (step S811). Next, the reading operation control unit 704 instructs the power supply control unit 711 to turn off (shut off) the power supply to the CIS sensor 701, the amplifier circuit 702, the A / D conversion unit 703, and the light source lighting unit 709. In response to an instruction from the reading operation control unit 704, the power control unit 711 turns off the power supply (step S812).

With this configuration, the power of the CIS sensor 701, the amplification circuit 702, the A / D conversion unit 703, and the light source lighting unit 709 is turned off while the reading operation is stopped, so that useless power can be reduced.

In the image reading apparatus, data stored in the buffer memory 709 is transferred to the host PC via the external I / F unit 710, and the reading operation is stopped until a certain amount of free space is created in the buffer memory 709. This stop time varies depending on the state of the host PC and the like. When the host PC is performing other heavy processing, it is necessary to wait for data transfer for a long time. During this time, the CIS sensor 701, the amplification circuit 702, the A / D conversion unit 703, and the light source lighting unit 709 do not need to do any work. Therefore, by turning off these power supplies, consumption during the intermittent reading mode is further increased. Electric power can be reduced.

  When the transfer of image data to the host PC, which is proceeding asynchronously while the reading operation is stopped, proceeds and the buffer memory 709 has a sufficient free space (Yes in step S813), the reading operation control is performed again. The unit 704 instructs the power supply control unit 711 to supply power to the CIS sensor 701, the amplifier circuit 702, the A / D conversion unit 703, and the light source lighting unit 709 that are in the cut-off state. Accordingly, the supply of power is resumed (step S814).

Thereafter, the reading operation control unit 704 supplies control signals to the CIS sensor 701, the amplification circuit 702, the A / D conversion unit 703, and the light source lighting unit 709 (step S815). In this way, the CIS sensor 701, the amplifier circuit 702, the A / D conversion unit 703, and the light source lighting unit 709 are started to operate, the drive control unit 708 is instructed to start driving, and the drive control unit controls the feed motor 707. Driven and resumes document conveyance (step S816). If it takes time until the CIS sensor 701, the amplifier circuit 702, the A / D converter 703, etc. operate stably, the process may wait for that time before executing step S816.

  When the above procedure is repeated and the image data for one page of the original is read (Yes in step S807), the driving of the feed motor and the transmission of the control signal are stopped (steps S808 and S809). Ends. In the configuration of this embodiment, after the buffer memory 709 runs out of free space, image data is transferred to the host PC, the scan operation is stopped for the time until the free space increases, and the control signal to each device is stopped. By turning off the power, useless power consumed by each device while the reading operation is stopped can be reduced. Note that when a plurality of documents are continuously read, the above scanning operation is repeated.

  The fourth embodiment of the present invention will be described below with reference to the drawings. First, FIG. 9 is a flowchart illustrating the operation of the image reading apparatus to which the present invention is applied. The outline of the image reading apparatus will be described below. The configuration of the main body and the circuit configuration are the same as those shown in FIGS. 2, 3, and 5 shown in the first embodiment and FIG. 7 shown in the third embodiment, but the CIS sensor used in this embodiment is The difference is that a return operation is required after stopping the operation or after turning on the power. The necessity of this return operation will be described. While the drive clock and line head signal supplied to the CIS sensor are stopped, the light source is not turned on. In the state where the light source is not turned on, the CIS sensor should originally not accumulate charges, but the CIS sensor accumulates charges due to the influence of external light, leakage current, and the like. If the state in which this charge is accumulated continues for a long time, the charge is saturated and the CIS sensor may not operate normally. In order to recover to the normal operation state once such a state is reached, it is necessary to perform a reset process in which the line head signal is input several times while the drive clock is supplied and the charge of the CIS sensor is discharged. is there.

  In FIG. 9, when a scan start is instructed from a connected host PC or the like, the reading operation control unit 704 outputs a drive clock and a line head signal to the CIS sensor 701 (step S901). By supplying a drive clock and a line head signal to the CIS sensor 701, dummy reading of a plurality of lines (for a predetermined number of reading times) is executed. The CIS sensor 701 starts accumulating charges in accordance with the line head signal and continues accumulating for a predetermined time, and then outputs the accumulated charges in accordance with the drive clock. By repeating this several times, unnecessary charges accumulated in the CIS sensor 701 when the operation is stopped are swept out and reset to recover to a normal operation state.

  The number of dummy readings for performing the recovery operation is as follows. As described in the second embodiment, by observing the output waveform from the CIS sensor 701 in advance, how many lines of dummy reading are required before recovery. In other words, it is possible to determine in advance how many times the line start signal should be input. The dummy reading is repeated until the line head signal is output for the number of times, and the recovery operation is performed (step S902). When the recovery operation is completed, the drive signal is also supplied to the amplifier circuit 702, the A / D converter 703, and the like (step S903).

  By inputting drive signals to the CIS sensor 701, the amplifier circuit 702, and the A / D conversion unit 703, image data can be input to the reading operation control unit 704. At this point, the document is still at the reading start position. Since it has not reached, the image data output at this point is unnecessary, and the reading operation control unit 704 does not capture this image data. Next, when an instruction to start driving is given to the drive control unit 708, the drive control unit drives the feed motor 707 and conveys the document (step S904).

  When the document reaches the reading start position (step S905), in order to start capturing image data, it is first checked whether there is enough space in the buffer memory 909 to capture image data (step S906). If there is sufficient free space in the buffer memory, image data is fetched line by line and transferred to the host PC (steps S907 and S908). Note that the transfer of image data is described as an example of synchronous transfer in step S908 as an example. However, if the host PC side can accept it, the transfer is performed asynchronously with respect to the reading operation. If the host PC side is not acceptable due to the busy state or the like, the image data is not transferred in step S908. The operations from step S906 to S908 are repeated for one page of the document. If it is determined in step S906 that there is not enough free space in the buffer memory due to a delay in taking image data at the host PC or the like, the image data cannot be taken in, so that the feed motor is driven to temporarily stop the reading operation. Is stopped (step S912). At this time, the reading operation control unit 704 outputs a signal related to the execution of the reading operation such as stopping the control signal supplied to the CIS sensor 701, the amplifier circuit 702, the A / D conversion unit 703, and the light source lighting unit 709. Stop (processing to make the supply stop state) is performed (step S913). Next, the reading operation control unit 704 instructs the power supply control unit 711 to turn off the power supply to the CIS sensor 701, the amplifier circuit 702, the A / D conversion unit 703, and the light source lighting unit 709. In response to an instruction from the reading operation control unit 704, the power control unit 711 turns off the power supply (step S914). Note that power consumption can be reduced without stopping the control signals supplied to the CIS sensor 701, the amplifier circuit 702, the A / D conversion unit 703, and the light source lighting unit 709, but the power is turned off. Since it is not preferable to continue supplying the control signal to the circuit, it is preferable to stop the control signal almost simultaneously with turning off the power.

  When the transfer of the image data to the host PC proceeding in parallel proceeds and a sufficient free space is made in the buffer memory 909 (step S915), the reading operation control unit 704 again causes the CIS sensor 701, the amplification circuit 702, The power supply control unit 711 is instructed to supply power to the A / D conversion unit 703 and the light source lighting unit 709, and the power supply control unit resumes power supply in accordance with this instruction (step S916).

  Next, the reading operation control unit 704 supplies a drive clock and a line head signal to the CIS sensor 701 (step S917). By doing so, as in step S901, the state in which charges are accumulated in the CIS sensor 701 when the operation is stopped and the indeterminate state immediately after the power is turned on are reset, and the normal operation state is restored. After performing the recovery operation by inputting the line head signal a predetermined number of times (step S918), the reading operation control unit 704 supplies control signals to the amplifier circuit 702, the A / D conversion unit 703, and the light source lighting unit 709 (step S918). S919). In this way, the CIS sensor 701, the amplifier circuit 702, the A / D conversion unit 703, and the light source lighting unit 709 are started to operate, the drive control unit 708 is instructed to start driving, and the drive control unit controls the feed motor 707. Driven and resumes document conveyance (step S920).

  When the above procedure is repeated and image data for one page of the original is read (Yes in step S909), driving of the feed motor and sending of the control signal are stopped (steps S910 and S911), and one page scan operation is performed. Ends.

  In the configuration of this embodiment, the scan memory is stopped and the control signal to each device is stopped until there is no more free space in the buffer memory 709, image data is transferred to the host PC, and the free space increases. After that, by turning off the power, it is possible to reduce useless power consumed by each device while the reading operation is stopped. Further, by operating the CIS sensor a certain number of times after the power is turned on again, the indeterminate state immediately after the power is turned on can be reset, and the reading operation can be resumed after the normal state. Note that when a plurality of documents are continuously read, the above scanning operation is repeated. It is also possible to use a combination of the constituent elements of the above embodiments, and these are included in the present invention.

1 is a block diagram illustrating a circuit configuration of an image reading apparatus according to a first embodiment. Sectional drawing which shows schematic structure of image reading apparatus Diagram showing the configuration of the line sensor Flowchart illustrating the operation of the image reading apparatus in the first embodiment. The figure for demonstrating transmission of the driving force of a separation feeding means Flowchart illustrating the operation of the image reading apparatus in the second embodiment. 4 is a block diagram illustrating a circuit configuration of an image reading apparatus according to a third embodiment. Flowchart illustrating the operation of the image reading apparatus in the third embodiment. Flowchart illustrating the operation of the image reading apparatus in the fourth embodiment.

DESCRIPTION OF SYMBOLS 1 Feed roller 2 Separation roller 3 Feed motor 11 CIS sensor 12 Amplification circuit 13 A / D conversion part 14 Reading operation control part 15 Light source 16 Light source lighting part 17 Feed motor 18 Drive control part 19 Buffer memory 20 External I / F part 100 Image Reading device 100C Paper feeding device (separate feeding means)
103 Line sensor 102a Conveying roller 103a Platen roller 104 Discharge roller 304 LED
305 LED
701 CIS sensor 702 Amplifying circuit 703 A / D conversion unit 704 Reading operation control unit 705 Light source 706 Light source lighting unit 707 Feed motor 708 Drive control unit 709 Buffer memory 710 External I / F unit 711 Power supply control unit

Claims (2)

A light source for illuminating the document;
An image reading sensor that receives reflected light from the document and converts it into an analog image signal;
An analog signal amplifier for amplifying the analog image signal;
A signal converter for converting the amplified analog image signal into a digital signal;
A transport section for transporting a document;
Control for shifting to a reading interruption state in which the conveyance and image reading of the document are temporarily interrupted during image reading from the document being conveyed, control for returning from the reading interruption state in order to resume image reading, and a document being conveyed Control means for performing control related to transmission of image data read from the external device;
In an image reading apparatus having
When the control unit shifts to the reading interruption state during execution of control related to transmission of image data to the external device, the control unit stops supplying a driving signal to the image reading sensor, and the analog signal amplification unit and the signal Controlling at least one of a power supply and a drive signal for at least one of the converters to be in a supply stop state,
The control means includes a sensor resumption drive means for supplying a predetermined number of drive signals to the image reading sensor when returning from the reading interruption state, and the sensor resumption driving means supplies the image reading sensor to the image reading sensor. The image reading apparatus is characterized in that, after supplying the drive signal for the number of times, the control means controls the at least one of the analog signal amplification unit and the signal conversion unit to return from the supply stop state. . A power control unit for turning on and off each power of the image reading sensor, the analog signal amplification unit, and the signal conversion unit;
In the reading interruption state, the control means performs control for stopping supply of drive signals to the image reading sensor, the analog signal amplifying unit, and the signal converting unit, and controls the power source control unit to include the image reading sensor, The image reading apparatus according to claim 1, wherein the image reading device is controlled to cut off the supply of power to the analog signal amplification unit and the signal conversion unit.

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