JP2010259279A - Electronic device, electronic device control method, image reader, and image reader driving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic device that allows use of a power supply having smaller rated power and efficiently achieves the reduction in costs and size of the power supply. <P>SOLUTION: The electronic device includes: a power storage element 303 for storing power of a power supply supplied from the outside; a plurality of loads 305 supplied with the power stored in the power storage element 303; and a control means 304 for selectively switching whether or not to supply power to each of the plurality of loads 305 on the basis of a voltage of the power storage element 303. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electronic apparatus such as an image reading apparatus including a power supply unit capable of supplying power to a connected load, a control method for the electronic apparatus, an image reading apparatus, and a driving method for the image reading apparatus.

  A power supply device built in an electronic device such as an image reading device or a printer stably supplies power consumed by loads such as a motor for conveying a document and a sensor for reading the document. It is necessary to have a rated power corresponding to the maximum value of the power consumption that changes.

  On the other hand, in order to reduce the cost of electronic equipment or to reduce the size of electronic equipment, it is necessary to reduce the cost or size of the power supply device, and in order to compensate for the accompanying decrease in power supply capacity, Various power supply configurations have been proposed.

  For example, the power supply unit includes two capacitors, and when one capacitor is connected to the load and drives the load, the rated power with which the load variation can be accommodated is small by controlling the other capacitor to be charged. An electronic device incorporating a power supply device has been proposed (Patent Document 1).

  In addition, a technique has been proposed that includes a constant voltage power supply device and a power storage power supply device, and connects these power supplies in parallel to supply power to a load, thereby reducing the rated power of the power supply device (Patent Document 2). ).

JP 2007-033752 A JP 2007-209149 A

  However, in the technique of Patent Document 1, even if the rated power of the power supply device can be reduced, if the number of capacitors is large, the cost increases and the size of the power supply also increases, thereby achieving cost reduction and downsizing. Can not do it.

  In the technique disclosed in Patent Document 2, when a constant voltage power supply device and a power storage power supply device are connected in parallel and power is supplied to the same load, unbalance such as the voltage of the power supply supplied from each is different. A circuit for eliminating the above becomes indispensable, the cost increases, and the size of the power source also increases. Therefore, similarly to the above-mentioned Patent Document 1, it is not possible to achieve cost reduction and size reduction.

  Further, in electronic devices such as relatively small image reading devices and printers driven by power supplied from the outside by an AC adapter or the like, it is desired to reduce the size and cost of the AC adapter that is carried with the device.

  In addition, there are the following problems in a relatively small electronic device such as an image reading apparatus or a printer that is driven by power supplied from the outside via an interface cable such as a USB.

  That is, the upper limit of the power supply current value supplied by the interface cable such as USB is set to 0.5 A at the maximum, for example, and driving a load such as a sheet conveyance motor having a large load fluctuation provides sufficient power. May not be able to be supplied, and performance may deteriorate.

  Therefore, the present invention can use a power supply unit with a small rated power in an electronic device, etc., reduce the cost and size of the power supply unit, and absorb load fluctuations when operating with power supply power supplied by an interface cable. And at least one of improving reliability.

  In order to achieve the above object, an electronic device according to the present invention includes a power storage element that stores power from an externally supplied power source, a first load that is driven by substantially constant power, and stabilization of the drive voltage. A second load that is not required, and the first load is connected to a charging path of a substantially constant voltage to the power storage element, and the second load has a voltage according to the voltage of the power storage element. It is connected to a discharge path from the electric storage element that changes.

  An electronic device according to the present invention includes a power storage element that stores power of a power source supplied from the outside, a first load that consumes substantially constant power, a second load that has a larger load variation than the first load, The first voltage is connected to a charging path to the power storage element, and the second load is a discharge path whose voltage changes according to the voltage of the power storage element, or power from the power storage element Are connected to a stabilized path.

  The electronic device of the present invention supplies power to each of the plurality of loads, a power storage element that stores power from an externally supplied power source, a plurality of loads to which the power stored in the power storage element is supplied, Switching means capable of switching whether or not to perform, and control means for controlling the switching means based on the voltage of the power storage element.

  An electronic device control method according to the present invention is a method for controlling an electronic device comprising: a power storage element that stores power from an externally supplied power source; and a plurality of loads that are supplied with power stored in the power storage element. A switching step for switching whether or not to supply power to each of the plurality of loads, and a control step for controlling switching in the switching step based on the voltage of the power storage element. Features.

  The image reading apparatus according to the present invention is supplied from the outside with an image reading unit that reads an image from a document, a moving unit that moves a relative position between the image reading unit and the document, a drive motor that drives the moving unit, and the like. A power storage element that stores power of the power source, and the power stored in the power storage element covers at least part of the drive current flowing through the drive motor, and the power stored in the power storage element is stored in the drive motor. The driving of the moving means is temporarily stopped.

  An image reading apparatus driving method according to the present invention includes an image reading unit that reads an image from a document, a moving unit that moves a relative position between the image reading unit and the document, a drive motor that drives the moving unit, and an external device. A power storage element that stores electric power of a power supply to be supplied, wherein the electric power stored in the power storage element covers at least a part of a drive current flowing through the drive motor, and When the electric power is stored in the electric storage element, the driving of the moving means by the driving motor is temporarily stopped.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to use a power supply part with small rated power, the electronic device which can implement | achieve efficiently the cost reduction and size reduction of a power supply part can be provided.

  In addition, according to the present invention, it is possible to provide an electronic device that can absorb load fluctuations and improve reliability when operated by power supply supplied by an interface cable.

It is a schematic sectional drawing for demonstrating the image reading apparatus which is 1st Embodiment of the electronic device of this invention. It is a schematic diagram of the principal part of the image reading apparatus shown in FIG. It is a block diagram which shows an example of the power supply part which supplies electric power to loads, such as a motor and a reading unit. It is a flowchart for demonstrating the operation example of a power supply part. It is a block diagram for demonstrating the power supply part of the image reading apparatus which is 2nd Embodiment of the electronic device of this invention. FIG. 5 is a flowchart for explaining processing for confirming a required amount of power of a load and detecting an operation state and abnormality of a load based on a rate of change of a voltage supplied from a power storage element to a load in a control unit of the control unit. . It is a block diagram for demonstrating the power supply part of the image reading apparatus which is 3rd Embodiment of the electronic device of this invention. It is a block diagram for demonstrating the power supply part of the image reading apparatus which is 4th Embodiment of the electronic device of this invention. It is a block diagram for demonstrating the power supply part of the image reading apparatus which is 5th Embodiment of the electronic device of this invention. It is a block diagram for demonstrating the power supply part of the image reading apparatus which is 6th Embodiment of the electronic device of this invention. It is a block diagram for demonstrating the power supply part of the image reading apparatus which is the 7th Embodiment of the electronic device of this invention. It is a flowchart for demonstrating the operation example of a power supply part. FIG. 13 is a block diagram for explaining an example in which the power supply unit of FIG. 12 is further embodied as a power supply unit of the image reading apparatus. FIG. 12 is a flowchart for explaining a process of switching the connection of a load based on the current limiting state of the current limiting unit in the power supply unit shown in FIG. 11.

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

(First embodiment)
FIG. 1 is a schematic cross-sectional view for explaining an image reading apparatus according to a first embodiment of the electronic apparatus of the present invention, and FIG. 2 is a schematic view of a main part of the image reading apparatus shown in FIG.

  As shown in FIGS. 1 and 2, in the image reading apparatus 200 of this embodiment, the document table 1 on which a plurality of documents F are stacked is driven up and down by a lifting motor 2. The document detection sensor 3 detects the document F stacked on the document table 1. The paper feed roller 4 is driven by a paper feed motor 5 and feeds a document F on the document table 1.

  The feeding roller 6 and the separation roller 7 are driven by a feeding motor 8 and a separation motor 9, respectively, and separate the documents F fed by the sheet feeding roller 4 one by one and feed them to the conveyance path. The paper feed motor 5, the feed motor 8, and the separation motor 9 are examples of the drive motor of the present invention. The paper feed roller 4, the feed roller 6, and the separation roller 7 constitute an example of a moving unit that moves a relative position between a document and a reading unit described later.

  The separation roller 7 always receives a rotational force for feeding the document F to the conveyance path from the separation motor 9 via a slip clutch (not shown). However, when the document F is one sheet, the separation roller 7 has a feeding force for the document F. In response to the slip clutch, the feeding roller 6 is allowed to follow and rotate. Then, when there are a plurality of documents F, the separation roller 7 rotates in a direction to return the documents F to the document table 1. A separation belt may be used in place of the separation roller 7.

  The conveyance motor 10 drives a pair of conveyance rollers 20 and 21 and a pair of conveyance rollers 22 and 23 for conveying the separated document F from the reading position to the discharge position. The nip gap adjusting motor 11 adjusts the gap between the feeding roller 6 and the separation roller 7 or the pressure contact pressure of the feeding roller 6 against the separation roller 7 to adjust the gap or pressure pressure suitable for the thickness of the document F. Thus, the separation and conveyance of the original F are performed smoothly.

  The reading units 14 and 15 include a line sensor that reads an image of the document F that has been conveyed and a light source for image reading. The light emitted from the light source is reflected by the reading surface of the document F, and the reflected light is reflected on the reading unit 14 and 15. When the line sensor receives light, the image of the document F is read.

  The paper discharge sensor 16 detects that the document F passes through the reading units 14 and 15 and is discharged to the paper discharge unit 44. The registration roller pairs 17 and 18 correct the skew of the document F by temporarily stopping and restricting the document F from being conveyed downstream. The registration clutch 19 transmits or blocks the rotation of the conveyance motor 10 to the registration roller 18.

  The conveyance roller pair 20, 21 and the conveyance roller pair 22, 23 convey the document F to the paper discharge unit 44. The two guide plates of the upper guide plate 40 and the lower guide plate 41 are sandwiched and transported between the roller pairs 6 and 7, the registration roller pairs 17 and 18, the transport roller pairs 20 and 21, and the transport roller pairs 22 and 23. Guide the document F.

  FIG. 3 is a block diagram showing an example of a power supply unit that controls power supply to loads such as the motors 2, 4, 8, 9, 10, 11 and the reading units 14, 15 while accumulating power from an external power supply. FIG.

  The power supply unit 300A shown in FIG. 3 is connected to an external power supply such as an AC adapter (not shown). When the power is turned on, the power supply unit 300A stores power in the power storage element 303 via the current limiting unit 302 connected to the charging path from the external power input unit 301 having an external input terminal, and loads 305 Supply power to That is, the power supply limiting unit 302 limits the current flowing into the circuit block provided with the power storage element 303.

  A power transmission path (discharge path) from the power storage element 303 to the load 305 is connected via a switch, and the power from the power storage element 303 is supplied to the load 305 such as a drive motor without being stabilized. As a result, the drive current flowing through the drive motor is covered by the current from the current limiting unit 302, and part of the drive current is supplied by the current from the power storage element 303. Note that when a large-capacity power storage element is used, even if the external power supply is cut off, all the drive current of the drive motor can be supplied from the power storage element for a while and the reading operation can be continued. . For example, an electric double layer capacitor that can be charged in a short time and has high charge / discharge durability is used for the power storage element 303. Note that the terminal voltage of the electricity storage element 303 is approximately proportional to the amount of electricity stored.

  Here, an advantage of current limiting by the current limiting unit 302 is that it is possible to prevent overloading of the external power source due to overcurrent at the time of charging the power storage element 303 and overload of the connected load. However, when the external power supply has an overload prevention function, for example, the current limiting unit 302 may be omitted and the external power supply input unit 301 and the storage element 303 may be directly connected.

  FIG. 4 is a flowchart for explaining an operation example of the power supply unit 300A. Here, the plurality of loads 305 will be described as a load 305-1, a load 305-2, and a load 305-3, respectively.

  When this process is started by supplying power from the external power supply input unit 301, the voltage detection unit 306 measures the terminal voltage of the power storage element 303 that increases due to the start of charging (step S1001).

  In step S1002, step S1005, and step S1008, the supply control unit 304 uses, for example, threshold 1 to threshold 3 based on how far the voltage value of the storage element 303 measured by the voltage detection unit 306 has increased. It is determined whether power is supplied to the loads 305-1 to 305-3. Here, the threshold value 1 to the threshold value 3 are set in consideration of the threshold value 1 <threshold value 2 <threshold value 3 and the load fluctuation rate, the minimum drive voltage, and the importance of the loads 305-1 to 305-3.

  In step S1002, the supply control unit 304 determines whether or not the measured voltage value of the power storage element 303 by the voltage detection unit 306 is equal to or greater than the threshold value 1. If the measured voltage value is equal to or greater than the threshold value 1, the process proceeds to step S1004. If the voltage value is less than the threshold value 1, the process proceeds to step S1003.

  In step S1004, the supply control unit 304 is in a state where the terminal voltage of the power storage element 303 reaches a predetermined voltage due to the progress of charging, and power can be supplied to the load 305-1. The power supply to the power supply is started, and the process proceeds to step S1005.

  In step S1003, since the terminal voltage of the electrical storage element 303 does not exceed the predetermined voltage, the supply control unit 304 stops if the supply of power to the load 305-1 has already started, and proceeds to step S1005.

  In step S1005, the supply control unit 304 determines whether or not the measured voltage value of the power storage element 303 by the voltage detection unit 306 is greater than or equal to the threshold value 2. If the measured voltage value is greater than or equal to the threshold value 2, the process proceeds to step S1007. If the voltage value is less than the threshold value 2, the process proceeds to step S1006.

  In step S1007, the supply control unit 304 determines that the terminal voltage of the power storage element 303 has reached a voltage that can supply power to the load 305-2 due to the progress of charging, and supplies power to the load 305-2. The process proceeds to step S1008.

  In step S1006, supply control unit 304 determines that the terminal voltage of power storage element 303 has not reached a predetermined voltage, stops the supply of power to load 305-2, and proceeds to step S1008.

  In step S1008, the supply control unit 304 determines whether or not the measured voltage value of the power storage element 303 by the voltage detection unit 306 is greater than or equal to the threshold 3, and if the measured voltage value is greater than or equal to the threshold 3, the process proceeds to step S1010. If the voltage value is less than the threshold 3, the process proceeds to step S1009.

  In step S1010, supply control unit 304 determines that the terminal voltage of power storage element 303 has reached a voltage at which power can be supplied to load 305-3 due to the progress of charging, and supplies power to load 305-3. The process proceeds to step S1011.

  In step S1009, supply control unit 304 determines that the terminal voltage of power storage element 303 has not reached the predetermined voltage, stops the supply of power to load 305-3, and returns to step S1002.

  The supply control unit 304 always charges the power storage element 303 within a range that does not exceed the current limit value of the current limit unit 302. However, the supply control unit 304 controls the current limit unit and the like to charge at a necessary timing. You may do it.

  Further, regarding the control in the supply control unit 304, control using a CPU may be used, or control using hardware such as a comparator may be provided by setting a threshold value for switching power supply start / stop. Each threshold value may be varied according to the operation state and operation mode of the apparatus, and the threshold value from the power supply state to the stop state and the threshold value from the stop state to the supply state may be changed as appropriate.

  As described above, in this embodiment, even if the current capacity of the external power supply is reduced, the necessary power can be supplied to the load 305 by discharging the power stored in the power storage element 303. .

  Further, since it is not necessary to use a charge control circuit that steps up and down the power storage element 303, the power supply unit 300A can be reduced in cost and size as a simple configuration using only the current limiting unit 302. Unlike the loads 305-1 to 305-3, a load (not shown) that requires stabilization of the power supply voltage is connected to a substantially constant voltage power supply path that receives power from the external power supply input unit 301. It is assumed that

(Second Embodiment)
Next, with reference to FIGS. 5 and 6, a power supply unit of an image reading apparatus which is a second embodiment of the electronic apparatus of the invention will be described. Note that portions overlapping or corresponding to those in the first embodiment will be described with reference to the drawings and symbols.

  FIG. 5 is a block diagram for explaining a power supply unit of the image reading apparatus according to the second embodiment of the present invention.

  In the present embodiment, as shown in FIG. 5, the terminal voltage value of the power storage element 303 of the power supply unit 300 </ b> B is monitored by the control unit 310. The control unit 310 includes an A / D converter 309 and a control unit 308, and the terminal voltage value of the power storage element 303 is converted into digital data by the A / D converter 309 and input to the control unit 308.

  When the power supply from the external power supply input unit 301 is started, the control unit 308 checks the terminal voltage value of the power storage element 303 because charging starts due to the inflow of current from the current limiting unit 302. Based on the terminal voltage value, the control unit 308 determines whether to supply power to the load 305 using a threshold value as in the first embodiment, and supplies power to the load 305. Switch between / stop.

  In this embodiment, the control unit 308 monitors a change in the terminal voltage of the power storage element 303 when power is supplied from the power storage element 303 connected via the current limiting unit 302 to the load 305. As a result, the current consumption value required by the load 305 can be confirmed, and the operating state and abnormality of the load can be detected.

  FIG. 6 illustrates a process in which the control unit 308 confirms a current consumption value required by the load 305 and detects an operating state or abnormality of the load based on the rate of change of the voltage supplied from the power storage element 303 to the load 305. It is a flowchart figure for demonstrating.

  When this process starts with power-on, charging of the storage element 303 starts with a predetermined current value limited by the current limiting unit 302 while the storage element 303 and all the loads 305 are left unconnected. Therefore, in step S1101, the control unit 308 checks the terminal voltage of the power storage element 303.

  In step S1102, control unit 308 calculates a normal value of the rate of increase of the terminal voltage of power storage element 303 from the current value of current limiting unit 302 and the capacity of power storage element 303.

  Then, the control unit 308 determines whether or not the increase rate of the terminal voltage during charging of the power storage element 303 is equal to or less than the threshold value determined from the normal value. Advances to step S1103.

  In step S1104, control unit 308 determines that storage element 303, current limiting unit 302, and the like are abnormal, and ends the process.

  In step S1103, the control unit 308 determines whether or not the terminal voltage has increased to the voltage threshold value due to charging of the storage element 303. If the terminal voltage has increased to the voltage threshold value, the process proceeds to step S1105, and charging is insufficient. Returns to step S1102.

  In step S1105, control unit 308 connects power storage element 303 and predetermined load 305 to supply power from power storage element 303 to load 305, and proceeds to step S1106.

  In step S1106, control unit 308 determines whether or not the current consumption value of load 305 obtained from the voltage change rate of power storage element 303 is within a predetermined range.

  Here, when the current value consumed by the connected load 305 is equal to or less than the current value limited by the current limiting unit 302, the voltage of the power storage element 303 further increases. Further, when the current consumption value consumed by the connected load 305 exceeds the limit current value limited by the current limit unit 302, the voltage of the power storage element 303 drops. From these, the current consumption value of the load 305 can be obtained.

  Therefore, when the consumption current value of the load 305 obtained from the change rate of the terminal voltage of the power storage element 303 is within a predetermined range, the control unit 308 determines that the load 305 is normal and proceeds to step S1108. In addition, when the current consumption value of the load 305 obtained from the rate of change in the terminal voltage of the power storage element 303 is out of the predetermined range, the control unit 305 determines that the load 305 is abnormal and proceeds to step S1107. It is desirable to make the above determination with the load 305 in a standard operating state. Also, the large load of the load change, it is desirable to recognize how much of the variation in advance.

  In step S1107, control unit 308 releases the connection between power storage element 303 and load 305, and ends the process.

  In step S1108, the control unit 308 stores the current consumption value of the load 305 obtained from the voltage change rate of the power storage element 303 when the load 305 is connected in a storage unit (not shown), and ends the process.

  The current consumption value stored here is used as information for determining a threshold value when determining whether or not the power storage element 303 and the load 305 can be connected in the subsequent normal operation. By performing the above processing for all the connected loads, it is possible to detect whether or not all the loads are abnormal.

  In the present embodiment, the load 305 is connected almost directly to the large-capacity storage element 303 via a switch. For this reason, even if the connected load 305 causes an overload state exceeding the current limit value, the voltage drop of the power storage element 303 is relatively gradual, and a sudden voltage drop due to load fluctuation can be avoided.

  Therefore, even when an excessive load is connected to the storage element 303, the connection between the storage element 303 and the load 305 may be released before malfunctioning due to a voltage drop. In particular, the load is a motor or the like, and the motor lock It is possible to avoid the malfunction of the entire apparatus in the case of an overload state due to the above. In addition, an abnormality detection element such as a fuse or a circuit mounted for each load is not necessary.

(Third embodiment)
Next, with reference to FIG. 7, a power supply unit of an image reading apparatus which is a third embodiment of the electronic apparatus of the present invention will be described. Note that portions overlapping or corresponding to those in the first embodiment will be described with reference to the drawings and symbols.

  FIG. 7 is a block diagram for explaining a power supply unit of an image reading apparatus according to the third embodiment of the present invention.

  In the present embodiment, as shown in FIG. 7, the power supply unit 400 has a plurality of power supply paths to the load 305, specifically, the load from the input side of the current limiting unit 302 and the terminal of the storage element 303. A path for supplying power to 305 is provided.

  Then, the supply control unit 304 is connected to the power supply power supply path or supplies power from the storage element 303 (discharge circuit) in consideration of the load fluctuation rate, the minimum drive voltage, and the importance of each load 305. Selectively control whether to connect to. The power source power supply path here is a path for supplying power from the external power source to the input side of the current limiting unit 302.

  For example, when the load 305 is a drive motor such as a DC motor, the load fluctuation rate is large, but even if the drive voltage is low, it can be handled by reducing the current consumption by reducing the rotation speed of the motor, which is large in operation. It doesn't matter. As for the power source for driving the digital circuit, there are many loads that operate without any problem even at a voltage of 2 V or less.

  However, white LEDs used for document illumination, for example, are characterized by small load fluctuations. On the other hand, when the power supply voltage decreases, a sufficient amount of light cannot be obtained, which hinders the image reading operation. In the present embodiment, since the output voltage of the electricity storage element 303 varies greatly depending on the state of the load, a white LED for document illumination or the like becomes defective due to a voltage drop when power is supplied from the electricity storage element 303.

  Therefore, in the present embodiment, the supply control unit 304 has a relatively small load fluctuation and the load (first load) 305 of the illumination system that requires a stable driving voltage on the input side of the current limiting unit 302. Select and connect the power supply path.

  In contrast, in the case of a load (second load) 305 (for example, a DC motor) with a large load fluctuation and a low minimum drive voltage, the supply control unit 304 selects a path for supplying power from the storage element 303. To do.

  When a path is selected to supply power from the power storage element 303, the supply control unit 304 uses the voltage value of the power storage element 303 measured by the voltage detection unit 306 as in the first embodiment. In addition, the supply / stop of power to the load 305 is switched using a threshold value.

  When the selection of the power supply path for the load 305 is changed, an intermittent start voltage is set as a threshold for shifting to an intermittent operation mode in which the reading operation of the image reading apparatus is stopped and power can be stored. To do. The intermittent start voltage is set based on the load having the highest minimum drive voltage among the loads 305 connected to the path for supplying power from the power storage element 303.

  For example, when the voltage of the storage element 303 is lower than the intermittent start voltage, the state is shifted to the intermittent operation mode, the operation of the apparatus is temporarily stopped, and the operation of the load 305 is stopped so that almost no power is consumed. To. Then, after the voltage of the storage element 303 has sufficiently increased, each load 305 is operated to restart the image reading operation. Note that it is desirable to change the intermittent start voltage every time the power supply path to each load 305 is changed by changing the operation state of the image reading apparatus, changing the external power source connected to the external power input unit 301, or the like.

  As described above, in the present embodiment, a configuration is provided in which a plurality of power supply paths are provided and a connection path of each load 305 can be selected from a plurality of different supply paths. Effective power path management can be performed by considering the drive voltage.

  Accordingly, the power stored in the storage element 303 can be efficiently used by recognizing a load that operates with a low drive voltage and a load that requires a high drive voltage and appropriately switching the connection path. The current limit value can be set in the current limiter from the supply control unit 304 or the like, and the current limit value is changed when the load connection path is changed. Further, the charging may be stopped by setting the current limit value to 0 or the like.

(Fourth embodiment)
Next, with reference to FIG. 8, a power supply unit of an image reading apparatus which is a fourth embodiment of the electronic apparatus of the present invention will be described. Note that portions overlapping or corresponding to those in the first embodiment will be described with reference to the drawings and symbols.

  FIG. 8 is a block diagram for explaining a power supply unit of an image reading apparatus according to the fourth embodiment of the present invention.

  In the present embodiment, as shown in FIG. 8, a charge / discharge circuit unit 406 is disposed on the output side of the current limiting unit 302, and the charge / discharge circuit unit 406 is directly connected to the load 305 via a switch. In addition, the storage element 303 is connected to the charge / discharge circuit unit 406, and an output in which the voltage is stabilized is generated from the terminal voltage of the storage element 303 and supplied to the load 305.

  Based on the voltage information of the storage element 303 obtained from the charge / discharge circuit unit 406, the supply control unit 304 switches supply / stop of power to the load 305 using a threshold value, as in the first embodiment.

  Regarding the control in the charge / discharge circuit unit 406 and the supply control unit 304, control using a CPU may be used, and threshold voltages for charge / discharge switching and power supply start / stop switching are provided, and hardware such as a comparator is provided. You may control using.

  In the present embodiment, even when the current capacity of the external power supply unit is reduced, stable power can be supplied to the supply destination load 305 by discharging while stabilizing the power stored in the power storage element 303. it can.

  In addition, by limiting the current value by the current limiting unit 302 to the current supplied from the outside to the charge / discharge circuit unit 406 and the power storage element 303, it is possible to prevent the external power source from being overloaded.

  Furthermore, by providing the charge / discharge circuit portion 406, overcharging of the power storage element 303 can be prevented, and even when the power storage element 303 is short-circuited, it can be safely protected.

  The voltage supplied from the charge / discharge circuit unit 406 to the load 305 is controlled to be a substantially constant voltage by a stabilization circuit (not shown) provided in the charge / discharge circuit unit 406. In the first embodiment, since the load 305 is connected almost directly to the power storage element 303, the threshold value for whether or not to connect is set to the minimum value of the load 305 in addition to the terminal voltage substantially proportional to the power storage amount of the power storage element 303 It must be set in consideration of the drive voltage.

  On the other hand, in this embodiment, it is not necessary to consider the minimum drive voltage of the load 305 to be connected, and when determining whether or not to connect the load by stabilizing the voltage according to the load 305 and keeping it substantially constant. The restriction condition is relaxed, and the electric power of the power storage element 303 can be used effectively. If the plurality of loads 305 have different power supply voltages, the output of the stabilization circuit also outputs a plurality of voltages.

(Fifth embodiment)
Next, a power supply unit of an image reading apparatus which is a fifth embodiment of the electronic apparatus of the present invention will be described with reference to FIG. Note that portions that overlap or correspond to the first and fourth embodiments will be described with reference to the drawings and reference numerals.

  FIG. 9 is a block diagram for explaining a power supply unit of an image reading apparatus according to the fifth embodiment of the present invention.

  In the present embodiment, as shown in FIG. 9, the power supply unit 600 has a path for supplying power whose voltage is stabilized to the load 305 through the current limiting unit 302 and the charge / discharge circuit unit 406 at the subsequent stage. The power supply unit 600 has a path for supplying power to the load 305 by connecting to the path (power supply power supply path) from the input side of the current limiting unit 302 without going through the charge / discharge circuit unit 406. Note that the circuit is not limited to the path from the input-side terminal of the current limiting unit 302, and may be a circuit in the previous stage, and may have a path for connecting the load 305 to the power supply path of substantially constant voltage. .

  Then, whether the supply control unit 304 supplies power to the load 305 through the charge / discharge circuit unit 406 or supplies power to the load 305 from the input side of the current limiting unit 302 without using the charge / discharge circuit unit 406. , Whether to stop the supply of power to the load 305 is determined.

  The terminal voltage of the power storage element 303 with voltage fluctuation is stabilized through the charge / discharge circuit unit 406. If necessary, boosting may be performed. When supplying power to the load 305 by connecting to such a discharge path, the supply control unit 304 uses the voltage information of the storage element 303 obtained from the charge / discharge circuit unit 406 as in the fourth embodiment. Based on this, the supply / stop of power to the load 305 is switched using a threshold value.

  Here, for the load 305 that is a substantially steady load, the current consumption is steady, and thus there is no effect of using the current limiting unit 302 or the power storage element 303. Therefore, in this embodiment, the current consumption expected for the steady load is set in advance, the steady load is connected to the input side of the current limiting unit 302, and the current consumption of the steady load is calculated from the current capacity of the external power source. The subtracted value is set as the current limit value of the current limiter 302.

  The current consumption of the steady load at this time may be set to a fixed value in advance for each load. Similarly to the first embodiment, each load 305 is connected to a path via the charge / discharge circuit unit 406 on a trial basis, information on the current value change from the current limiting unit 302, and the terminal voltage of the storage element 303. The current consumption may be obtained from the rate of change.

  In the present embodiment, the power storage element 303 is charged within the current limit value determined by the current limiter 302, and at the same time, power is supplied to the load 305 having a large load fluctuation through the power storage element 303. Thereby, the change of the current consumption by the load 305 with a large load fluctuation | variation can be smoothed effectively.

  In addition, by supplying power to the load 305 that consumes steady power without passing through the current limiting unit 302 or the charging / discharging circuit unit 406, the maximum current value passing through the current limiting unit 302 or the charging / discharging circuit unit 406 can be increased. The control element can be reduced in size.

(Sixth embodiment)
Next, a power supply unit of an image reading apparatus which is a sixth embodiment of the electronic apparatus of the present invention will be described with reference to FIG. Note that portions overlapping or corresponding to the first and fifth embodiments will be described with reference to the drawings and reference numerals.

  FIG. 10 is a block diagram for explaining a power supply unit of an image reading apparatus according to the sixth embodiment of the present invention.

  In the present embodiment, as illustrated in FIG. 10, the power supply unit 700 includes a plurality of external power supply input units 301 and current limiting units 302.

  The power supply unit 700 has a path for supplying power to the load 305 through the charge / discharge circuit unit 406 and a path for supplying power from the external power supply input unit 301 to the load 305 without going through the charge / discharge circuit unit 406. Have.

  The supply control unit 304 supplies power to the load 305 through the charge / discharge circuit unit 406, supplies power from the external power input unit 301 to the load 305 without using the charge / discharge circuit unit 406, or loads It is determined whether to stop supplying power to 305.

  When power is supplied to the load 305 via the charging / discharging circuit unit 406, the supply control unit 304 is based on the voltage information of the storage element 303 obtained from the charging / discharging circuit unit 406, as in the fifth embodiment. In addition, the supply / stop of power to the load 305 is switched using a threshold value.

  Here, when the characteristics of the load 305 are known in advance, if the load has a large load fluctuation, power is supplied via the current limiting unit 302 and the charge / discharge circuit unit 406, and if the load is a steady load, the current limiting is performed. The power is supplied without passing through the unit 302 and the charge / discharge circuit unit 406.

  In addition, a value obtained by subtracting the total current consumption (required current value) of the steady load from the current capacity of the external power supply using the current consumption of the steady load obtained in advance is set as the current limit value of the current limiting unit 302. .

  The charging / discharging circuit unit 406 charges the power storage element 303 within the current limit value, and at the same time, supplies power to a load having a large load fluctuation among the plurality of loads 305 via the power storage element 303. Thereby, the change of the current consumption by the load with a large load fluctuation can be effectively smoothed.

  In addition, when the power supply specification of the external power supply input unit 301 is known, power is supplied from the external power supply input unit having a smaller power supply capacity for the steady load, and the power supply capacity is larger for the variable load. It is also possible to supply power from an external power input unit.

  Accordingly, it is possible to more efficiently achieve smoothing of power supply to the variable load by efficiently using the power supplied from the outside. In the power supply unit 700 including the plurality of external power input units 301, the load Electric power can be efficiently supplied to 305.

(Seventh embodiment)
Next, a power supply unit of an image reading apparatus which is a seventh embodiment of the electronic apparatus according to the invention will be described with reference to FIGS. Note that portions that overlap or correspond to the first, fifth, and sixth embodiments will be described with reference to the drawings and symbols.

  FIG. 11 is a block diagram for explaining a power supply unit of an image reading apparatus according to the seventh embodiment of the present invention.

  In the present embodiment, as illustrated in FIG. 11, the power supply unit 800 includes a plurality of external power supply input units 301.

  The power supply unit 800 has a path for supplying power to the load 305 through the charge / discharge circuit unit 406 and a path for supplying power from the external power supply input unit 301 to the load 305 without going through the charge / discharge circuit unit 406. Have.

  The supply control unit 304 supplies power to the load 305 through the charge / discharge circuit unit 406, supplies power from the external power input unit 301 to the load 305 without using the charge / discharge circuit unit 406, or loads It is determined whether to stop supplying power to 305.

  When power is supplied to the load 305 via the charge / discharge circuit unit 406, the supply control unit 304 uses the voltage information of the storage element 303 acquired from the charge / discharge circuit unit 406, as in the sixth embodiment. Based on this, the supply / stop of power to the load 305 is switched using a threshold value.

  When power is supplied from the external power supply input unit 301 to the load 305, the supply control unit 304 performs the same control as in the fifth embodiment.

  Here, in the present embodiment, the supply control unit 304 can obtain the status information of the external power supply connected to the external power supply input unit 301. In general, the state information of the external power supply is often determined by the voltage of the external power supply. As a simple means, there is a method using a means for judging whether or not an input voltage exceeds a certain threshold value, and a method using a control changing means for changing a control signal output according to the input voltage. As a complicated means, a load that consumes a constant load current may be connected, and an input voltage change due to the load current may be examined and judged. As a more complicated and advanced means, there is a method in which a dedicated control signal input from an external power source can be output to the external power input unit 301, and status information of the external power source is obtained by this control signal. In the present embodiment, any of the above-described means may be used.

  In the present embodiment, the supply control unit 304 determines from the external power supply connection information whether an external power supply is connected to the external power supply input unit 301. If the external power supply is connected, the supply control unit 304 determines the number and type of external power supplies. Based on this, the connection state of the power supply path in the power supply unit 800 is changed.

  The external power supply connection information for the above control includes the detection result of the voltage of the connected external power supply and the location of the connected input unit, information set by the user by an external power supply state setting unit (not shown), etc. Either one is used.

  In addition, when an external power source is connected to the external power source input unit 301, the external power source is connected to the charge / discharge circuit unit 406 via the current limiting unit 302 and a constant current defined by the current limiting unit 302 is passed. It is also possible to obtain information on the external power supply using the voltage change of.

  When the power is turned on, the power storage element 303 is sufficiently discharged, and there is a sufficient time until the power storage is completed. By using this time, it is possible to realize a state in which a load for supplying a constant current is connected from the external power supply input unit 301 via the current limiting unit 302, and information on the external power supply can be acquired.

  Next, an operation example of the power supply unit 800 will be described with reference to FIG. Here, two external power input units 301 will be described as an external power input unit 301-1 and an external power input unit 301-2.

  In step S1201, the supply control unit 304 connects the external power input unit 301-1 to the current limiting unit 302, and proceeds to step S1202. At this time, the supply control unit 304 sets the current limit value of the current limit unit 302 to 0 and does not supply power to the charge / discharge circuit unit 406. The current limit value may not be set to 0, but the connection may be disconnected.

  In step S1202, the supply control unit 304 measures the voltage of the external power input unit 301-1, stores it in a storage unit (not shown), and proceeds to step S1203.

  In step S1203, the supply control unit 304 determines whether the voltage measurement value stored in step S1202 is greater than or equal to a threshold value. If the voltage measurement value is equal to or greater than the threshold, the supply control unit 304 proceeds to step S1204. If the voltage measurement value is not equal to or greater than the threshold, the supply control unit 304 determines that no external power source is connected to the external power input unit 301-1. Then, the process proceeds to step S1209.

  In step S1204, the supply control unit 304 sets the current limit value of the current limiter 302 to a low value in order to continuously measure the load characteristics, and the process proceeds to step S1205. Here, in order to cope with external power sources having different characteristics, the current value is gradually increased without suddenly increasing. As for the set value of the current limit value, it is desirable to prepare only for the type of external power supply to be connected.

  In step S1205, the supply control unit 304 measures the voltage of the external power input unit 301-1, stores it in a storage unit (not shown), and proceeds to step S1206.

  In step S1206, the supply control unit 304 determines whether the voltage measurement value stored in step S1205 is greater than or equal to a threshold value. If the voltage measurement value is equal to or greater than the threshold, the supply control unit 304 proceeds to step S1207. If the voltage measurement value is not equal to or greater than the threshold, the external power source connected to the external power input unit 301-1 is unusable. Determination is made and the process proceeds to step S1209.

  In step S1207, the supply control unit 304 sets the current limit value of the current limiter 302 to a high value, and the process proceeds to step S1208.

  In step S1208, the supply control unit 304 measures the voltage of the external power input unit 301-1, stores it in a storage unit (not shown), and proceeds to step S1209.

  In step S1209, the supply control unit 304 returns the current limit value of the current limiter 302 to 0, disconnects the external power input unit 301-1, and proceeds to step S1210.

  Thereafter, in steps S1210 to S1218, the same processing from steps S1201 to S1209 is performed on the external power input unit 301-2. By performing the operation so far until the power storage element 303 is sufficiently charged, it is possible to detect the connection state information of the external power source without connecting to a useless load.

  In addition, when the charging voltage of the power storage element 303 has already increased substantially the same as the voltage of the external power supply input unit 301, the load characteristics described in the previous embodiment are measured, and the voltage of the power storage element 303 decreases. Then, the wasteful power can be eliminated by performing the processing of FIG.

  The load 305 is allocated to the external power source determined by the setting of the external power source connection state and the detection of the external power source connection state information.

  As a method for obtaining the characteristics of the load 305 to be connected, a method for setting in advance in the same manner as described in the above-described embodiment, and a method for detecting by using the current value of the current limiting unit 302 by sequentially connecting loads. There is. By using the characteristics of the load 305 thus obtained, the external power supply input unit 301 is directly connected in order from the load with less load fluctuation so as not to exceed the current capacity of the external power supply.

  At this time, if the maximum total current value (a value including the load fluctuation) by the total load is lower than the total supply current value of the external power supply, all of the external power supply input unit 301 and the load 305 may be directly connected. . At this time, the operations of the current limiting unit 302, the charge / discharge circuit unit 406, the power storage element 303, and the like may be stopped.

  By controlling in this way, it is possible to reduce the number of circuits relaying from the external power supply input unit to the load, and to reduce power consumption in the relaying circuit unit.

  When the maximum total current value of the connected load exceeds the current capacity of the external power supply, a load greater than the excess load is connected to the current limiting unit 302. In particular, it is desirable to connect a load with a large load fluctuation to the output side of the charge / discharge circuit unit 406. As a result, the maximum current value is leveled by the storage element 303 for a load having a large load fluctuation. In the present embodiment, a motor drive circuit or the like is assumed as a load having a large load fluctuation.

  Further, the current limit value of the current limiting unit 302 at this time is equal to or less than a value obtained by subtracting the maximum total current value corresponding to the direct connection of the external power input unit 301 and the load 305 from the maximum supply current value of the external power source. Adjusted. By adjusting in this way, control is performed so that the maximum total current value of the load connected to the external power supply input unit 301 does not exceed the current capacity of the external power supply.

  As a result, it is possible to more effectively achieve smoothing of the power supply to the variable load by efficiently using the power input from the outside. Further, by stopping unused circuits such as the current limiting unit 302 and the charge / discharge circuit unit 406 in accordance with the connection state of the external power input unit 301, overall energy saving can be achieved. Therefore, the power supply unit 800 including the plurality of external power supply input units 301 can efficiently supply power to the load 305.

  FIG. 13 is a block diagram for explaining an example in which the power supply unit 800 of FIG. 12 is further embodied as the power supply unit of the image reading apparatus.

  In the power supply unit 900 shown in FIG. 13, a USB power supply from the host device is connected to the external power supply input unit 301-1, and another USB power supply from the host device, an AC adapter, or a battery is connected to the external power supply input unit 301-2. Connected.

  In the load 305, a conveyance motor 305-1, a CIS sensor 305-2 of a reading unit for the front surface, an illumination LED 305-3, a CIS sensor 305-4 of a reading unit for the back surface, and an illumination LED 305-5 are arranged. In addition, a registration sensor 305-6, a document detection sensor 305-7, and a memory 305-8 are arranged in the load 305.

  The memory 305-8 is a memory for storing image-processed data, and includes a RAM or a non-volatile memory as necessary. The memory 305-8 may be configured to be detachable from the apparatus via an I / F such as a connector.

  The USB power source connected to the external power input unit 301-1 is a power source supplied from the USB interface, and includes a low power mode with a low power supply capability and a high power mode with a high power supply capability. Information on the difference in power supply capability can be obtained through communication with an external device via the USB interface.

  The USB power supply, AC adapter, or battery connected to the external power input unit 301-2 has a difference in output voltage and power supply capability. The difference in the power supply capability is not only the difference in the type of power supply but also the same. Differences occur even with different types of power supplies. Therefore, confirming in advance the power supply capability of the power source connected to the external power input unit 301-2 is very effective in increasing the efficiency of the apparatus.

  The current limiting unit 302 limits the supply current value to the charging / discharging circuit unit 406 that controls charging / discharging to the power storage element 303. This current limit value can be changed by setting.

  The storage element 303 is composed of an electric double layer capacitor or the like, and is not charged in most cases when the power is turned on. Until the charging of the storage element 303 is completed, a current substantially equal to the current limit value flows through the current limiter 302. At this time, the connection for charging the power storage element 303 from the USB power supply connected to the external power supply input unit 301-1 is stopped, and the connection is changed to the connection charged by the power from the external power supply input unit 301-2. As a result, a large load can be applied to another USB power source, AC adapter, battery, or the like connected to the external power input unit 301-2. Then, by detecting the voltage change rate of the external power input unit 301-2 at this time, the type of power source connected to the external power input unit 301-2 and the power supply capability can be confirmed.

  In addition, by using the state of charging the power storage element 303 to acquire information about the external power supply, a sufficient load is applied to the power supply unit, and at the same time, the flowing current is used to charge the power storage element 303. You can also prevent waste.

  The supply control unit 304 switches the connection of each of the loads 305-1 to 305-8 in consideration of the operation state of the image reading apparatus, the connection state of the external power input units 301-1 and 301-2, and the load state. In order to determine whether or not there is a load with large load fluctuation among the loads 305-1 to 305-8, the load is simply connected to the charge / discharge circuit unit 406, and the voltage change of the power storage element 303 is determined. Based on the rate, fluctuations in current consumption of each load can be obtained.

  For example, the necessary power of the conveyance motor 305-1 or the like greatly varies depending on the motor efficiency, the friction of the conveyance unit, and the like. On the other hand, it is well known that the illumination LEDs 305-3 and 305-5 have a large difference in the amount of emitted light due to fluctuations in the power supply voltage.

  With the above operation, the power supply capability of the power supply unit 900 and the required power of the loads 305-1 to 305-8 can be accurately obtained.

  Next, the supply control unit 304 appropriately changes the connection of the loads 305-1 to 305-8 in consideration of the operation state of the image reading apparatus.

  For example, a case will be described in which nothing is connected to the external power input unit 301-2 and only the USB power source of the external power input unit 301-1 operates.

  The supply control unit 304 always operates, and the load 305 having a relatively small load fluctuation and a small current consumption is directly connected to the USB power source in a range not exceeding the USB power supply upper limit of the external power input unit 301-1. Thereafter, the supply control unit 304 sets the current limit value of the current limit unit 302 to a value obtained by subtracting the current consumption for the load 305 directly connected to the USB power source from the upper limit value of the USB power source of the external power input unit 301-1. Change settings.

  Next, the supply control unit 304 connects the load 305 having a large load fluctuation to the current limiting unit 302 and connects the remaining load 305 to the output side of the charge / discharge circuit unit 406. The load 305 connected to each unit may not be connected depending on the operation state of the image reading apparatus.

  By making such a connection, even when the operation mode is an operation mode that consumes more current than the power supplied by the USB power supply, for example, one or more readings are completed using charging / discharging of the storage element 303. In addition, an intermittent operation that takes a pause time for charging can be performed. This makes it possible to sequentially read a plurality of documents. At the same time, it is possible to cope with load fluctuations due to the operating state of the apparatus even if the storage capacity of the storage element 303 is small. As a result, in an image reading apparatus that is operated by power supply supplied by an interface cable for a USB interface or the like, it is possible to absorb load fluctuations and improve reliability. The intermittent operation mode may be an operation mode in which a pause time for charging is taken in the middle of reading one original.

  Next, a case where a power source is connected to the external power input unit 301-2 will be described.

  When the supply control unit 304 determines that the power source connected to the external power input unit 301-2 has sufficient power supply capability by the above-described means, the load 305 corresponding to the power source is input to the external power source. Connect directly to the unit 301-2.

  For example, when it is known that the power source connected to the external power input unit 301-2 is another USB power source from the external device, the load 305 within a range not exceeding the USB power supply capability is input to the external power source. Connected to the unit 301-2. The remaining load 305 having a large load fluctuation is connected to the output side of the discharge circuit unit 406.

  Next, in the case where an AC adapter or the like having a relatively high power supply voltage stability and a high power supply capability is connected to the external power supply input unit 301-2, the supply control unit 304 includes all loads 305-1 to 305. -8 is directly connected to the external power input unit 301-2.

  In this case, a path for supplying power from the external power supply input unit 301-2 to the power storage element 303 may be cut. As a result, power can be supplied to the load without going through the current limiting unit 302 and the charge / discharge circuit unit 406, and wasteful power consumption can be eliminated.

  In addition, when it is known that a battery having a low power supply capability is connected to the external power input unit 301-2, the supply control unit 304 connects the load 305 so as not to use the power of the battery as much as possible.

  For example, a small load 305 with relatively little fluctuation, and a load 305 with a relatively high power supply voltage that is required have a USB power supply for the external power input unit 301-1 within a range that does not exceed the power supply capability of the external power input unit 301-1. Connect directly to.

  Next, the supply control unit 304 connects the battery of the external power input unit 301-2 to the current limiting unit 302, and then connects the remaining load to the charge / discharge circuit unit 406. As a result, a load with little load fluctuation, that is, a load that constantly consumes power is connected to the USB power source of the external power input unit 301-1, and battery consumption due to a steady load can be avoided.

  Further, the discharge limit of the battery can be set by the current limiting unit 302, and at the same time, the occurrence of a malfunction due to the decrease in the battery voltage due to the load fluctuation can be effectively avoided by using the storage element 303.

  FIG. 14 is a flowchart for explaining the process of switching the connection of the load 305 based on the current limiting state of the current limiting unit 302 in the power supply unit 800 shown in FIG.

  In step S1301, the supply control unit 304 checks the current limiting state of the current limiting unit 302 when connecting any one of the two external power supply input units 301 and any of the plurality of loads 305. Here, the current limit value of the current limiting unit 302 is set to, for example, the upper limit value of the power supplied to the external power supply input unit.

  Then, when the value of the current flowing through the current limiting unit 302 is substantially equal to the current limiting value of the current limiting unit 302, that is, the supply control unit 304 reaches the upper limit value of the current limiting value, the supply control unit 304 operates the image reading apparatus. Hold on. When supply control unit 304 confirms that the value of the current flowing through current limiting unit 302 has become less than the current limit value due to factors such as completion of charging of power storage element 303, processing proceeds to step S <b> 1302.

  In step S1302, the supply control unit 304 sets a value obtained by subtracting the required current value of the load 305 to be connected from the upper limit value of the power supplied from the external power input unit 301 as the current limit value of the new current limit unit 302. The process proceeds to S1303.

  In step S1303, when the supply control unit 304 confirms that the current value flowing through the current limiting unit 302 has become less than the new current limit value, the process proceeds to step S1304.

  In step S1304, the supply control unit 304 directly connects the load 305 to the external power input unit 301 and ends the process.

  Thereby, when connecting the load 305 from the current limiting unit 302 to the input side, it is possible to avoid the external power input unit 301 from being overloaded and to detect the timing of connection change with high accuracy. .

  As described above, the power supply capability of the external power input unit 301 and the required power of the load 305 are detected in a timely manner, and the power supply control is performed accordingly, so that power can be used effectively and reliable image reading can be performed with less power. Can operate. Further, an unnecessarily large element can be used as the power storage element 303 necessary for the image reading operation.

  In addition, this invention is not limited to what was illustrated by said each embodiment, In the range which does not deviate from the summary of this invention, it can change suitably.

  For example, in each of the above embodiments, the image reading apparatus that conveys an original and reads an image has been described. However, a flat head scanner or the like that reads an image from a stationary original may be used. Further, it may be a printer or an external storage device that does not have an image reading function. In addition, the components of the above embodiments may be added to other embodiments and are included in the present invention.

  The object of the present invention can also be achieved by executing the following processing. That is, a storage medium that records a program code of software that realizes the functions of the above-described embodiments is supplied to a system or apparatus, and a computer (or CPU, MPU, etc.) of the system or apparatus is stored in the storage medium. This is the process of reading the code.

  In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the program code and the storage medium storing the program code constitute the present invention.

  Moreover, the following can be used as a storage medium for supplying the program code. For example, floppy (registered trademark) disk, hard disk, magneto-optical disk, CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD + RW, magnetic tape, nonvolatile memory card, ROM or the like. Alternatively, the program code may be downloaded via a network.

  Further, the present invention includes a case where the function of the above-described embodiment is realized by executing the program code read by the computer. In addition, an OS (operating system) running on the computer performs part or all of the actual processing based on an instruction of the program code, and the functions of the above-described embodiments are realized by the processing. Is also included.

  Furthermore, a case where the functions of the above-described embodiment are realized by the following processing is also included in the present invention. That is, the program code read from the storage medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. Thereafter, based on the instruction of the program code, the CPU or the like provided in the function expansion board or function expansion unit performs part or all of the actual processing.

F Document 1 Document platen 2 Lifting motor 3 Document detection sensor 4 Paper feed roller 5 Paper feed motor 6 Feeding roller 7 Separating roller 8 Feeding motor 9 Separating motor 10 Carrying motor 11 Nip gap adjusting motors 14, 15 Reading unit 16 Discharging sensor 17, 18 Registration roller 19 Registration clutch 20, 21 Conveying roller 22, 23 Conveying roller 200 Image reading device 300A Power supply unit 301 External power input unit 302 Current limiting unit 303 Power storage element 304 Supply control unit 305 Load 306 Voltage detection unit 310 Control unit 406 Charge / discharge circuit

Claims (12)

A power storage element for storing power from an externally supplied power source;
A first load driven by substantially constant voltage power;
A second load that does not require stabilization of the drive voltage,
The first load is connected to a substantially constant voltage power supply path through which power is supplied from the power supply;
The second load is connected to a discharge path from the power storage element that changes in voltage according to the voltage of the power storage element.
An electronic device characterized by that. A power storage element for storing power from an externally supplied power source;
A first load consuming substantially constant power;
A second load having a larger load variation than the first load,
The first load is connected to a power supply path through which power is supplied from the power supply,
The second load is connected to a discharge path from the power storage element that changes in voltage according to the voltage of the power storage element, or a path where power from the power storage element is stabilized.
An electronic device characterized by that. The electronic apparatus according to claim 1, further comprising a stabilization circuit that stabilizes a voltage of electric power output from the power storage element. A power storage element for storing power from an externally supplied power source;
A plurality of loads to which electric power stored in the electric storage element is supplied;
Switching means capable of switching whether to supply power to each of the plurality of loads;
An electronic device comprising: control means for controlling the switching means based on a voltage of the power storage element. Current limiting means for limiting the current flowing into the circuit block provided with the storage element,
The switching means is capable of switching so as to connect each of the plurality of loads to a power supply power supply path through which power from the power source is supplied to the current limiting means or before it.
The control means performs control to switch between connecting to the power supply power supply path or connecting to the discharge path from the power storage element for each of the plurality of loads based on the state of the plurality of loads.
The electronic device according to claim 4. Charging means for charging power from a power source supplied from the outside to the power storage element;
The control means obtains voltage information of the storage element from the charging means;
The electronic device according to claim 4. The switching means can be switched to connect each of the plurality of loads to a power supply path for supplying power from the power source to the charging means or to the preceding stage.
The control unit is configured to control whether to connect each of the plurality of loads to the power supply power supply path or to the discharge path from the power storage element based on the magnitude of load fluctuation of the plurality of loads. I do,
The electronic apparatus according to claim 6. Limiting the current flowing into the circuit block provided with the storage element, comprising a current limiting means capable of setting a current limit value,
The switching means can be switched so as to connect each of the plurality of loads to a power supply power supply path through which power from the power source is supplied to the current limiting means or before it.
The control means sets the current limiting means to a value substantially equal to or less than a value obtained by subtracting the total current consumption value of loads connected to the power supply path from the upper limit value of the current supplied from the outside. Set as current limit value of
The electronic device according to claim 4. Current limiting means for limiting the current flowing into the circuit block provided with the storage element, and a plurality of power input units for supplying power from the outside,
The control means determines whether to connect the load directly to the power input unit based on connection state information of the power input unit.
The electronic device according to claim 4. A power storage element for storing power from an externally supplied power source;
A method for controlling an electronic device comprising: a plurality of loads to which power stored in the power storage element is supplied,
A switching step for switching whether to supply power to each of the plurality of loads;
A control step of controlling switching in the switching step based on a voltage of the power storage element. A method for controlling an electronic device. Image reading means for reading an image from a document;
Moving means for moving the relative position between the image reading means and the document;
A drive motor for driving the moving means;
A power storage element that stores power from an externally supplied power source,
Covering at least part of the drive current flowing through the drive motor with the electric power stored in the storage element,
When the voltage of the power storage element falls below a predetermined value, the drive of the moving means by the drive motor is temporarily suspended;
An image reading apparatus. Image reading means for reading an image from a document;
Moving means for moving the relative position between the image reading means and the document;
A drive motor for driving the moving means;
A storage element that stores power from an externally supplied power source, and a driving method of an image reading apparatus comprising:
Covering at least part of the drive current flowing through the drive motor with the electric power stored in the storage element,
When the voltage of the power storage element falls below a predetermined value, the drive of the moving means by the drive motor is temporarily suspended;
A method for driving an image reading apparatus.