JP6162963B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus having a power saving function.

  Conventionally, an image reading apparatus that optically reads a document placed on a document table is known. When such an image reading apparatus reads an original, the original size sensor circuit detects the size of the original on the original table.

  The document size sensor circuit detects the size of the document on the document table when the opened document table cover is in a semi-closed state when it is closed. This is because the document size sensor circuit detects the document size by the light reflected from the document, and therefore detects the light reflected by the document table cover when the document table cover is completely closed. This is because the correct document size cannot be detected.

  Some image reading apparatuses as described above have a power saving function. In such an image reading apparatus, for example, when there is no operation from the user for a predetermined time, the normal mode is shifted to the power saving mode. On the other hand, the return from the power saving mode to the normal mode is performed by opening the document table cover when the document table cover is closed and the mode is shifted to the power saving mode. When the document table cover is open and the mode is shifted to the power saving mode, when the document table cover is closed, the power saving mode is returned to the normal mode.

  In the power saving mode, power supply to the document size sensor circuit is stopped. When returning from the power saving mode to the normal mode, power supply to the document size sensor circuit is resumed.

  As described above, the return from the power saving mode to the normal mode is performed by opening and closing the document table cover. In the half-closed state when the document table cover is closed, the document size sensor circuit detects the document size. If the document size sensor circuit is not yet in a state where the document size can be detected when the document table cover is in a semi-closed state when the document table cover is closed, the document size detection fails.

  On the other hand, in the image reading apparatus of Patent Document 1, a power saving circuit having a small circuit scale is constructed in an FPGA (Field Programmable Gate Array) in the power saving mode. Since this power saving circuit can communicate with the document size sensor circuit, when returning from the power saving mode to the normal mode, the CPU resumes power supply to the document size sensor circuit in a short time and performs a predetermined initialization process. Can be done. When the initialization process ends, the document size can be detected. In this way, the image reading apparatus of Patent Document 1 shortens the time until the document size can be detected when returning from the power saving mode to the normal mode while maintaining the power saving effect.

JP 2009-124375 A

  However, the document size sensor circuit cannot perform the initialization process until the power is stabilized even when the power supply is resumed. In the image reading apparatus disclosed in Patent Document 1, after the power supply to the document size sensor circuit is resumed, the document size cannot be detected until the power stabilization period and the initialization process have elapsed. Here, the power stabilization period is longer than the initialization process time.

  For this reason, in the image reading apparatus of Patent Document 1, when returning to the normal mode, depending on how the user closes the document table cover, the document size sensor is still in the half-closed state when the document table cover is closed. There is a possibility that the document size detection may fail because the circuit is not ready to detect the document size.

  The present invention has been made in view of the above, and an object of the present invention is to provide an image reading apparatus that can reduce the failure of document size detection when returning from the power saving mode to the normal mode while maintaining the power saving effect.

  In order to achieve the above object, the first feature of the image reading apparatus according to the present invention is that the image reading apparatus operates based on one of a normal mode for executing image reading processing and a power saving mode in which power consumption is lower than that of the normal mode. An image reading apparatus comprising: a document table on which a document is placed; a document table cover that opens and closes relative to the document table; a cover open detection unit that detects an open / closed state of the document table cover; and the document table Document size detecting means for detecting the size of the document on the document table in a semi-closed state when the cover is shifted from the open state to the closed state, and the normal mode and the power saving mode according to predetermined conditions Control means for switching, and an integrated circuit that is connected to the control means and the document size detection means and constructs a logic circuit therein based on circuit information. In the normal mode, the normal circuit for executing the image reading process is constructed in the integrated circuit, and communicates with the document size detecting unit when the normal mode is shifted to the power saving mode. A power saving circuit having a circuit scale smaller than the time circuit is constructed in the integrated circuit, and when the document table cover is in an open state, the power supply to the document size detecting means in the normal mode is continued, and the document When the table cover is in the closed state, the power supply to the document size detecting means is stopped, and the power saving mode is restored when returning from the power saving mode to the normal mode due to a change in the opening / closing state of the document table cover. If the power supply to the document size detecting means is stopped in step 1, the power supply is restarted, and the document size detecting means is connected to the power saving circuit. Certain to be activated.

  A second feature of the image reading apparatus according to the present invention is further provided with measurement means for measuring a speed at which the original table cover is closed, and the control means is configured to close the original table cover measured by the measurement means. Controls whether or not to continue power supply to the document size detection means when the document table cover is in the open state when shifting from the normal mode to the power saving mode based on the speed history. There is to do.

  According to the first feature of the image reading apparatus of the present invention, a power saving time circuit that communicates with the document size detecting means is constructed in the integrated circuit when shifting from the normal mode to the power saving mode. At the same time, when the document table cover is in the open state, the power supply to the document size detection unit in the normal mode is continued, and when the document table cover is in the closed state, the power supply to the document size detection unit is stopped. When the power supply to the document size detection means is stopped in the power saving mode when returning to the normal mode due to the change in the open / close state of the document table cover, the power supply is resumed and the power saving circuit is turned on. The document size detecting means is activated.

  Thereby, when returning from the power saving mode to the normal mode, there is no need to wait for the reconstruction of the logic circuit in the integrated circuit. For this reason, when the document table cover is closed in the power saving mode, the document size detection means is activated to detect the document size after the document table cover is opened and before the document table cover is half closed. It becomes possible to make it possible. Further, when the document table cover is open in the power saving mode, the power supply to the document size detecting unit is continued even in the power saving mode, so that the document size detecting unit is in a state where the document size can be detected. Therefore, the image reading apparatus can reduce the failure in detecting the document size when returning from the power saving mode to the normal mode regardless of whether the document table cover in the power saving mode is in the closed state or in the open state.

  Further, since the circuit scale of the power saving circuit is small, the power for holding the circuit can be kept small. In addition, when the document table cover is in the closed state during the transition from the normal mode to the power saving mode, the power supply to the document size detection unit is stopped.

  Therefore, according to the first feature of the image reading apparatus according to the present invention, it is possible to reduce the document size detection failure when returning from the power saving mode to the normal mode while maintaining the power saving effect.

  According to the second feature of the image reading apparatus according to the present invention, when the document table cover is in the open state during the transition from the normal mode to the power saving mode based on the history of the speed at which the document table cover is closed. The control unit controls whether or not the power supply to the document size detecting means is continued. As a result, it is possible to increase the power saving effect while suppressing the failure of document size detection when returning from the power saving mode to the normal mode.

1 is a block diagram illustrating a schematic configuration of an image reading apparatus according to an embodiment. 1 is an external view of an image reading apparatus according to an embodiment. 6 is an explanatory diagram of a wake-up position of a document table cover and a document size detection limit position. FIG. FIG. 3 is a block diagram illustrating a characteristic functional unit of the image reading apparatus according to the embodiment. It is a flowchart of the transfer process from normal mode to power saving mode. It is a flowchart of the transfer process from power saving mode to normal mode. 6 is a timing chart showing changes in the state of the FPGA and document size sensor circuit when shifting from the power saving mode to the normal mode when the document table cover is closed in the power saving mode. (A) shows that when the document table cover is open in the power saving mode, the power saving mode is changed to the normal mode when the power supply to the document size sensor circuit is stopped as in the closed state. 6 is a timing chart showing changes in the state of the FPGA and the document size sensor circuit during the transition. (B) shows the FPGA and document size when shifting from the power saving mode to the normal mode when the document table cover is open in the power saving mode and the power supply to the document size sensor circuit is continued. It is a timing chart which shows the change of the state of a sensor circuit. It is a flowchart of the switching process of a power saving transfer mode.

  Embodiments of the present invention will be described below with reference to the drawings. Throughout the drawings, the same or equivalent parts and components are denoted by the same or equivalent reference numerals. However, it should be noted that the drawings are schematic and different from the actual ones. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  Further, the embodiment described below exemplifies an apparatus or the like for embodying the technical idea of the present invention, and the technical idea of the present invention is to arrange the components and the like as follows. It is not something specific. The technical idea of the present invention can be variously modified within the scope of the claims.

  FIG. 1 is a block diagram showing a schematic configuration of an image reading apparatus 10 according to an embodiment of the present invention, and FIG. 2 is an external view of the image reading apparatus 10.

  The image reading apparatus 10 employs a flat bed method in which a read original is fixed and read. As shown in FIGS. 1 and 2, the image reading apparatus 10 includes an apparatus main body 100 including a document table 110 on which a document P to be read is placed, and a document table cover 120 that opens and closes the document table 110. And an auto sheet feeder 130 that is integrated with the document table cover 120 and automatically sends the document to the document table 110.

  The apparatus main body 100 is provided with an image reading unit 140 including a line sensor in which image reading elements such as a CCD are arranged on a line, a light source, a carriage on which the line sensor is mounted, a motor for conveying the carriage, and the like. The apparatus main body 100 is provided with a control circuit 150 including a CPU, a signal processing device, a communication processing device, and the like. Furthermore, the apparatus main body 100 is provided with a power supply circuit 160 that supplies power to each unit.

  A cover open sensor (corresponding to a cover open detection means) 170 is provided in the vicinity of a connection portion between the apparatus main body 100 and the document table cover 120. Cover open sensor 170 detects the open / closed state of document table cover 120. Specifically, the cover open sensor 170 detects whether or not the document table cover 120 is open with respect to the document table 110 or closed. The cover open sensor 170 detects that the document table cover 120 has passed the wake-up position and has passed the document size detection limit position.

  Here, the document table cover 120 is in the open position shown by a solid line in FIG. 3 in the open state. In the closed state, the document table cover 120 is in the closed position indicated by a two-dot chain line in FIG. The document table cover 120 is formed in a rectangular shape, and opens and closes with respect to the document table 110 by rotating around one side.

  The wake-up position is a position of the document table cover 120 indicated by a broken line in FIG. 3, and is a position where the angle θ formed by the document table cover 120 and the document table 110 becomes the wake-up angle θ1. The wake-up angle θ1 is smaller than the angle formed by the document table cover 120 and the document table 110 in the open position.

  The document size detection limit position is the position of the document table cover 120 indicated by a one-dot chain line in FIG. 3, and is the position where the angle θ between the document table cover 120 and the document table 110 becomes the document size detection limit angle θ2. Document size detection limit angle θ2 is smaller than wake-up angle θ1.

  In the present embodiment, the state where the document table cover 120 is in a position satisfying θ2 ≦ θ ≦ θ1 is referred to as a semi-closed state.

  The image reading apparatus 10 operates based on one of the normal mode and the power saving mode. The normal mode is a mode for executing image reading processing. In the normal mode, the image reading apparatus 10 consumes a certain amount of power because it is on standby so that it can immediately respond to the user's operation even when the image reading process is not being performed. The power saving mode is a mode that consumes less power than the normal mode by stopping power supply to a predetermined circuit, stopping some functions, and the like. The image reading apparatus 10 cannot perform image reading processing in the power saving mode.

  The transition from the normal mode to the power saving mode is performed when a predetermined condition is satisfied. Here, in the image reading apparatus 10, the automatic power saving transition mode or the manual power saving transition mode is selected as the power saving transition mode that is a mode related to the transition condition from the normal mode to the power saving mode. In the automatic power saving transition mode, the image reading apparatus 10 transitions to the power saving mode when no operation from the user is accepted for a predetermined time in the normal mode. In the manual power saving transition mode, when the image reading apparatus 10 receives an instruction to shift to the power saving mode from a printer (not shown) as a host apparatus in the normal mode, the image reading apparatus 10 shifts to the power saving mode.

  FIG. 4 is a block diagram illustrating characteristic functional units of the image reading apparatus 10. For simplicity, functional parts that are not important in the description of the present embodiment are omitted.

  As shown in FIG. 4, the control circuit 150 includes a CPU (corresponding to the control means in the claims) 20, a RAM 30, a flash memory 40, an FPGA 50, an FeRAM 60, a USB interface 70, and a system bus that connects each part. 80. Here, the FPGA 50 is an integrated circuit capable of configuring a logic circuit by loading (configuring) circuit information.

  The flash memory 40 stores program and configuration circuit information in a nonvolatile manner. The RAM 30 is a work area for the CPU 20. The CPU 20 configures circuit information in the FPGA 50 according to the program recorded in the flash memory 40. In the FPGA 50 used in the present embodiment, the logic circuit volatilizes when the power supply is cut off. Therefore, in order to hold the configured logic circuit, it is necessary to supply power according to the scale of the logic circuit.

  The circuit information for configuration and the program may be recorded in separate flash memories.

  The image reading unit 140 includes a document size sensor circuit (corresponding to document size detection means in claims) 90 for detecting the size of the document P placed on the document table 110. The document size sensor circuit 90 includes a size sensor 91 in which a plurality of sets of light receiving elements are arranged corresponding to a standard size, and a communication circuit 92 that communicates with the FPGA 50. In the present embodiment, the document size sensor circuit 90 determines the document size by the light blocked by the document P. Therefore, the document size sensor circuit 90 detects the document size by using external light when the document table cover 120 is in a half-closed state.

  When the image reading apparatus 10 is in the power saving mode and the open / close state of the document table cover 120 is changed manually by the user, the image reading apparatus 10 needs to shift to the normal mode in preparation for image reading processing. Therefore, the cover open sensor 170 monitors the open / close state of the document table cover 120 without sleeping even in the power saving mode.

  On the other hand, as will be described later, when the document table cover 120 is closed when the document size sensor circuit 90 shifts from the normal mode to the power saving mode, the power supply is stopped in the power saving mode. If the document table cover 120 is in the open state when shifting from the normal mode to the power saving mode, the power supply to the document size sensor circuit 90 is continued even in the power saving mode.

  In the present embodiment, two types of circuit information are recorded in the flash memory 40. One is circuit information configured in the FPGA 50 in the normal mode. This circuit information includes circuit information for constructing a logic circuit necessary for image reading processing. The other is characteristic circuit information of the present embodiment that is configured in the FPGA 50 in the power saving mode. Hereinafter, the former circuit information is referred to as “normal circuit information”, and the latter circuit information is referred to as “power saving circuit information”.

  The circuit information for constructing a logic circuit that performs processing for detecting a signal from the cover open sensor 170 and notifying the CPU 20 and a logic circuit that performs communication processing with the document size sensor circuit 90 are included in the circuit information during power saving. And are included. Based on these pieces of circuit information, an open / close detection circuit 51 and a communication circuit 52 are constructed in the FPGA 50. The open / close detection circuit 51 detects a signal from the cover open sensor 170 in the power saving mode and performs processing for notifying the CPU 20 of the signal. The communication circuit 52 performs communication processing with the document size sensor circuit 90.

  As described above, the logic circuit constructed by the circuit information during power saving is a circuit that performs the minimum necessary processing in the power saving mode. For this reason, the circuit scale can be made much smaller than the logic circuit constructed by the circuit information at the normal time. Accordingly, the power required to hold the logic circuit in the power saving mode can be reduced as compared with the case where the logic circuit required for the image reading process is held.

  In the FeRAM 60, various adjustment values unique to the body of the image reading apparatus 10 are recorded in a nonvolatile manner.

  Connected to the USB interface 70 is a USB cable for connecting the printer serving as the host device and the image reading apparatus 10.

  Next, a characteristic operation of the image reading apparatus 10 in the present embodiment will be described. FIG. 5 is a flowchart of a transition process from the normal mode to the power saving mode. Here, in the normal mode, normal-time circuit information is configured in the FPGA 50, and a normal-time circuit necessary for image reading processing is constructed. Note that a logic circuit constructed with the normal circuit information is referred to as a “normal circuit”, and a logical circuit constructed with the power save circuit information is referred to as a “power save circuit”.

  In the normal mode, the CPU 20 determines whether or not the state of the image reading apparatus 10 satisfies a predetermined condition for shifting to the power saving mode (step S1). As described above, in the automatic power saving transition mode, the transition condition to the power saving mode is that no operation from the user is accepted for a predetermined time in the normal mode. In the manual power saving mode, the condition for shifting to the power saving mode is that an instruction to shift to the power saving mode is received from the printer as the host device.

  When the condition for shifting to the power saving mode is satisfied (step S1: YES), the CPU 20 configures the power saving time circuit information in the FPGA 50 and constructs the power saving time circuit (step S2). At this time, the normal circuit may be deleted. Thereafter, a predetermined initialization process is performed to start the operation as a power saving circuit.

  Next, the CPU 20 determines whether or not the document table cover 120 is closed based on a signal from the cover open sensor 170 (step S3).

  When the document table cover 120 is in the closed state (step S3: YES), the CPU 20 stops the power supply to the document size sensor circuit 90, performs other predetermined processing, and shifts to the power saving mode. On the other hand, when the document table cover 120 is in the open state (step S3: NO), the CPU 20 performs other predetermined processing while continuing to supply power to the document size sensor circuit 90 and shifts to the power saving mode. To do.

  Here, in the power saving mode, the power supply to the cover open sensor 170 is continued. The FPGA 50 operates as a power saving circuit and monitors a signal from the cover open sensor 170.

  Next, processing when shifting (returning) from the power saving mode to the normal mode will be described with reference to the flowchart of FIG. The conditions for shifting from the power saving mode to the normal mode include that a document has been placed on the auto sheet feeder 130 and that an operation panel (not shown) has accepted an operation. The case where the power saving mode is changed to the normal mode on condition that the opening / closing state of 120 is changed will be described.

  In the power saving mode, the CPU 20 determines whether or not the open / close state of the document table cover 120 has changed (step S11).

  Specifically, when the document table cover 120 is closed in the power saving mode, the CPU 20 determines that the open / close state of the document table cover 120 has changed when the document table cover 120 is opened. The document table cover 120 is closed in the power saving mode when the document table cover 120 is closed during the transition from the normal mode to the power saving mode, as described with reference to the flowchart of FIG. is there. Here, when the document table cover 120 in the closed state is opened and opened in the power saving mode, a signal is sent from the cover open sensor 170 to the open / close detection circuit 51 of the FPGA 50. Based on the signal, the open / close detection circuit 51 notifies the CPU 20 that the document table cover 120 has been opened.

  On the other hand, when the document table cover 120 is open in the power saving mode, the CPU 20 determines that the open / close state of the document table cover 120 has changed when the wake-up position is reached in the process of closing the document table cover 120. The document table cover 120 is open in the power saving mode when the document table cover 120 is open during the transition from the normal mode to the power saving mode, as described with reference to the flowchart of FIG. is there. Here, when the document table cover 120 opened in the power saving mode reaches the wake-up position, a signal is sent from the cover open sensor 170 to the open / close detection circuit 51 of the FPGA 50. Based on the signal, the open / close detection circuit 51 notifies the CPU 20 that the document table cover 120 has reached the wake-up position.

  When the open / close state of the document table cover 120 changes (step S11: YES), the CPU 20 determines whether power supply to the document size sensor circuit 90 is stopped (step S12).

  Here, as described with reference to the flowchart of FIG. 5, the power supply to the document size sensor circuit 90 is stopped when the document table cover 120 is closed when the normal mode is shifted to the power saving mode. This is the case. In this case, in step S11, it is determined that the open / close state of the original platen cover 120 has changed due to the original platen cover 120 being changed from the closed state to the open state.

  The reason why the power supply to the document size sensor circuit 90 is not stopped (the power supply is continued) is when the document table cover 120 is open at the time of transition from the normal mode to the power saving mode. is there. In this case, in step S11, it is determined that the open / close state of the document table cover 120 has changed because the document table cover 120 has reached the wake-up position from the open state.

  When the power supply to the document size sensor circuit 90 is stopped (step S12: YES), the CPU 20 restarts the power supply to the document size sensor circuit 90 (step S13).

  Thereafter, the CPU 20 communicates with the document size sensor circuit 90 via the communication circuit 52 of the FPGA 50 to execute an initialization process (step S14). As a result, the document size sensor circuit 90 is activated.

  When the document table cover 120 is changed from the closed state to the open state, when the power supply to the document size sensor circuit 90 is restarted and the document size sensor circuit 90 is activated, the CPU 20 brings the document table cover 120 into the half-closed state. It is determined whether or not (step S15). Here, the document table cover 120 is semi-closed when the opened document table cover 120 reaches the wake-up position in the process of being closed by the user.

  When the document table cover 120 is in a semi-closed state (step S15: YES), the document size sensor circuit 90 that has completed the initialization process detects the document size (step S16). The detection result is notified to the CPU 20 via the communication circuit 52 of the FPGA 50.

  Thereafter, the CPU 20 configures the normal-time circuit information in the FPGA 50 and constructs the normal-time circuit (step S17). When the normal circuit is constructed, the power saving circuit may be deleted. Thereafter, the normal circuit starts operation by performing a predetermined initialization process. The normal time circuit information configuration and initialization process takes some time, but it is sufficient if it can be performed before the start of the image reading process.

  On the other hand, when power supply to the document size sensor circuit 90 is continued in the power saving mode (step S12: NO), restart of power supply to the document size sensor circuit 90 and initialization of the document size sensor circuit 90 are performed. unnecessary. For this reason, after step S12, step S13 and step S14 are omitted, and the process proceeds to step S15, and the subsequent processing is performed.

  Next, changes in the state of the FPGA 50 and the document size sensor circuit 90 when shifting from the power saving mode to the normal mode by the processing of the flowchart of FIG. 6 described above will be described.

  First, refer to the timing chart of FIG. 7 for changes in the state of the FPGA 50 and the document size sensor circuit 90 when shifting from the power saving mode to the normal mode when the document cover 120 is closed in the power saving mode. To explain.

  As described above, when the document table cover 120 is closed in the power saving mode, the power supply to the document size sensor circuit 90 is stopped. A power saving circuit is constructed in the FPGA 50.

  When the document table cover 120 is opened and opened at time t1, the power supply to the document size sensor circuit 90 is resumed as described above, and the initialization process is executed.

  The initialization process of the document size sensor circuit 90 is performed after the power is stabilized. The time (power stabilization period) from the restart of power supply at time t1 to time t2 when the power stabilizes is, for example, about 100 ms. The initialization process is generally completed in a shorter time than the power stabilization period. From time t3 when the initialization process ends, the document size sensor circuit 90 enters a state in which the document size can be detected.

  In the case of FIG. 7, the timing at which the document size sensor circuit 90 detects the document size is the timing when the document table cover 120 is opened and then closed to reach the wake-up position in the process of being closed. By then, the initialization processing of the document size sensor circuit 90 can be finished, and the document size sensor circuit 90 can be brought into a state where the document size can be detected.

  Here, unlike the present embodiment, circuit information is volatilized from the FPGA 50 when power supply to the FPGA 50 is stopped without constructing a power saving circuit in the FPGA 50 in the power saving mode. In this case, when returning to the normal mode, it is necessary to configure and initialize the normal-time circuit information in the FPGA 50 to construct the normal-time circuit. The CPU 20 can communicate with the document size sensor circuit 90 only after a normal circuit is constructed in the FPGA 50, and can activate the document size sensor circuit 90. For this reason, as compared with the present embodiment, it takes a long time until the document size sensor circuit 90 becomes capable of detecting the document size. Therefore, before the document size sensor circuit 90 becomes capable of detecting the document size, the document table cover 120 passes the document size detection limit position and is not semi-closed, and the document size detection may fail.

  On the other hand, in the present embodiment, the power saving circuit can communicate with the document size sensor circuit 90. Therefore, when returning from the power saving mode to the normal mode, the CPU 20 immediately supplies power to the document size sensor circuit 90. To start. As a result, it is possible to shorten the time until the document size sensor circuit 90 becomes capable of detecting the document size. As a result, the document size detection failure can be reduced. Further, since the circuit scale of the power saving circuit is small, the power for holding the circuit can be kept small.

  Next, the timing chart of FIG. 8 shows changes in the state of the FPGA 50 and the document size sensor circuit 90 when shifting from the power saving mode to the normal mode when the document table cover 120 is in the open state in the power saving mode. The description will be given with reference.

  FIG. 8A is a timing chart when power supply to the document size sensor circuit 90 is stopped in the power saving mode even when the document table cover 120 is in the open state, as in the closed state. . FIG. 8B is a timing chart when the document table cover 120 is in the open state in the power saving mode and the power supply to the document size sensor circuit 90 is continued. FIG. 8B is a timing chart when the document table cover 120 is in the open state in the power saving mode of the present embodiment, and FIG. 8A is the present embodiment shown for comparison. It is a different timing chart.

  In the case of FIG. 8A, power supply to the document size sensor circuit 90 is stopped in the power saving mode. A power saving circuit is constructed in the FPGA 50. In this case, when the document table cover 120 reaches the wake-up position at time t11 in the process of closing the document table cover 120, the power supply to the document size sensor circuit 90 is resumed and the initialization process is executed. From time t13 when the power is stabilized and the initialization process is completed, the document size sensor circuit 90 enters a state in which the document size can be detected.

  If the user quickly closes the document table cover 120 from the open state, the document table cover 120 may pass the document size detection limit position at time t12 before time t13 as shown in FIG. If the time from when the document table cover 120 reaches the wake-up position to the document size detection limit position is smaller than the sum of the power stabilization period and the initialization processing time, the document table cover 120 is Passes the document size detection limit position. In this case, at time t13, the document table cover 120 is not in the half-closed state, and the document size sensor circuit 90 fails to detect the document size.

  On the other hand, in the case of FIG. 8B, power is supplied to the document size sensor circuit 90 even at time t11, and the document size can be detected. Therefore, at time t11, the document size sensor circuit 90 detects the document size, and the detection result is notified to the CPU 20 via the communication circuit 52 of the FPGA 50. Therefore, even if the user closes the document table cover 120 quickly, the CPU 20 can acquire the document size.

  Next, the power saving transition mode will be described.

  In the present embodiment, when the image reading apparatus 10 is turned on, the automatic power saving transition mode is set. When connected to a printer as a host device via the USB interface 70, the image reading device 10 is changed to a manual power saving transition mode in accordance with an instruction from the host device. Therefore, the image reading apparatus 10 is basically set to the manual power saving transition mode when connected to the host apparatus, and shifts from the normal mode to the power saving mode in accordance with an instruction from the host apparatus. . However, the mode can be changed to the automatic power saving transition mode by a user operation or the like.

  Incidentally, the connection between the image reading apparatus 10 and the host apparatus may be disconnected. Switching processing of the power saving transition mode at this time will be described with reference to the flowchart of FIG.

  In a state where the image reading device 10 is connected to the host device, the CPU 20 determines whether or not the connection with the host device is disconnected (step S21).

  When the connection with the host device is disconnected (step S21: YES), the CPU 20 stores the power saving transition mode (automatic power saving transition mode or manual power saving transition mode) at the time of disconnection in the RAM 30 (step S22).

  Next, the CPU 20 sets the automatic power saving transition mode as the power saving transition mode of the image reading apparatus 10 (step S23). In other words, when the manual power saving transition mode is set when the connection with the host device is disconnected, the mode is switched to the automatic power saving transition mode. If the automatic power saving transition mode is set when the connection with the host device is disconnected, the automatic power saving transition mode is maintained.

  Thereafter, the CPU 20 determines whether or not the host device is reconnected to the image reading device 10 (step S24).

  When the host device is reconnected to the image reading apparatus 10 (step S24: YES), the CPU 20 returns the power saving transition mode of the image reading apparatus 10 to the mode stored in the RAM 30 in step S22.

  By the switching process of the power saving transition mode as described above, even if the manual power saving transition mode is set in the image reading apparatus 10 when the connection with the host apparatus is disconnected, the image is read after the connection with the host apparatus is disconnected. The reader 10 is set to the automatic power saving transition mode. As a result, the image reading apparatus 10 can shift from the normal mode to the power saving mode even when the connection with the host apparatus is disconnected.

  Further, when the host device is reconnected, the image reading apparatus 10 returns to the power saving transition mode at the time of disconnection. Therefore, even when the disconnection from the host device is temporarily disconnected due to noise, the original power saving transition is performed. Can return to mode.

  When the connection with the host device is disconnected and then another host device is connected, the image reading apparatus 10 maintains the automatic power saving transition mode even after the connection. In this case, the new host device newly sets the power saving transition mode through communication with the image reading device 10.

  As described above, the image reading apparatus 10 causes the FPGA 50 to construct a power saving circuit that communicates with the document size sensor circuit 90 when shifting from the normal mode to the power saving mode. At the same time, power supply to the document size sensor circuit 90 in the normal mode is continued when the document table cover 120 is in the open state, and power supply to the document size sensor circuit 90 is performed when the document table cover 120 is in the closed state. Stop. When the power supply to the document size sensor circuit 90 is stopped in the power saving mode when returning to the normal mode due to the change in the open / close state of the document table cover 120, the power supply is resumed to save power. The original size sensor circuit 90 is activated in the circuit.

  Thereby, when returning from the power saving mode to the normal mode, there is no need to wait for reconfiguration of the logic circuit in the FPGA 50. Therefore, when the document table cover 120 is in the closed state in the power saving mode, the document size sensor circuit 90 is activated after the document table cover 120 is opened until the document table cover 120 is semi-closed in the closing process. The document size can be detected. When the document cover 120 is open in the power saving mode, the power supply to the document size sensor circuit 90 is continued even in the power saving mode. Therefore, the document size sensor circuit 90 is in a state where the document size can be detected. is there. As a result, even when the document table cover 120 is quickly closed, power stabilization and initialization processing are not required, and the document size can be detected immediately. Therefore, the image reading apparatus 10 can reduce document size detection failure when returning from the power saving mode to the normal mode regardless of whether the document table cover 120 in the power saving mode is in the closed state or in the open state.

  Further, since the circuit scale of the power saving circuit is small, the power for holding the circuit can be kept small. Further, when the document table cover 120 is in the closed state during the transition from the normal mode to the power saving mode, the power supply to the document size sensor circuit 90 is stopped.

  Therefore, the image reading apparatus 10 can reduce the failure of document size detection when returning from the power saving mode to the normal mode while maintaining the power saving effect.

  A history of the speed at which the document table cover 120 is closed is taken, and based on this history, when the document table cover 120 is in the open state when shifting from the normal mode to the power saving mode, the document size sensor circuit 90. You may make it control whether the electric power supply to is continued.

  In the above embodiment, when the document table cover 120 is open in the power saving mode, power supply to the document size sensor circuit 90 is continued even in the power saving mode. As described above, since the power supply to the document size sensor circuit 90 is started from the time when the wake-up position is reached in the process of closing the document table cover 120, the document size sensor circuit 90 can detect the document size. This is because the document table cover 120 may pass through the document size detection limit position before entering the state, and the document size detection may fail.

  However, depending on the speed at which the document table cover 120 is closed, the document size can be detected even if the power supply to the document size sensor circuit 90 is started from the time when the document table cover 120 reaches the wake-up position. That is, when the time period from when the document table cover 120 reaches the wake-up position until it reaches the document size detection limit position is greater than the total of the power stabilization period, the initialization process time, and the document size detection time, The document size sensor circuit 90 can detect the document size in the half-closed state of the document table cover 120. Therefore, the document size can be detected even if the power supply to the document size sensor circuit 90 is started from the time when the document table cover 120 reaches the wake-up position.

  Therefore, a history of the speed at which the document table cover 120 is closed is taken, and if it is determined that the document table cover 120 is rarely closed at a speed faster than the reference speed based on the history, power saving is performed from the normal mode thereafter. When shifting to the mode, the power supply to the document size sensor circuit 90 may be stopped even when the document table cover 120 is open. For example, when the document table cover 120 is closed at a speed equal to or lower than the reference speed for a predetermined number of times or more, even when the document table cover 120 is in an open state during the transition from the normal mode to the power saving mode thereafter. The power supply to the document size sensor circuit 90 may be stopped.

  Thereby, it is possible to enhance the power saving effect while suppressing the failure of the document size detection when returning from the power saving mode to the normal mode.

  Here, the reference speed is the time from when the document table cover 120 reaches the wake-up position until it reaches the document size detection limit position, the power stabilization period in the document size sensor circuit 90, the initialization processing time, and the document The speed is equal to the total time required for size detection.

  The speed A at which the document table cover 120 is closed is calculated by the following equation (1).

A = (θ1-θ2) / (t1-t2) (1)
Here, t1 is the time when it is detected by the cover open sensor 170 that the document table cover 120 has passed the wake-up position in the process of closing the document table cover 120. t <b> 2 is the time when it is detected by the cover open sensor 170 that the document table cover 120 has passed the document size detection limit position while the document table cover 120 is closed.

  When the document table cover 120 is closed, when the cover open sensor 170 detects that the document table cover 120 has passed the wake-up position and the document size detection limit position, the CPU 20 detects the document table cover 120 according to the equation (1). The closing speed A is calculated. The CPU 20 and the cover open sensor 170 constitute the measuring means in the claims. A history of the speed A at which the document table cover 120 is closed is stored in the FeRAM 60.

  Even when the document table cover 120 is in the open state as described above, the document table cover 120 may be closed at a speed faster than the reference speed after the power supply to the document size sensor circuit 90 is stopped. In the subsequent transition from the normal mode to the power saving mode, if the document table cover 120 is in the open state, the power supply to the document size sensor circuit 90 may be continued.

  The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiments. For example, some components may be deleted from all the components shown in the embodiment.

10 Image reading device 20 CPU
30 RAM
40 Flash memory 50 FPGA
51 Open / close detection circuit 52 Communication circuit 60 FeRAM
70 USB interface 80 System bus 90 Document size sensor circuit 91 Size sensor 92 Communication circuit 100 Main body 110 Document table 120 Document table cover 130 Auto sheet feeder 140 Image reading unit 150 Control circuit 160 Power supply circuit 170 Cover open sensor

Claims (2)

An image reading apparatus that operates based on one of a normal mode that executes image reading processing and a power saving mode that consumes less power than the normal mode,
A document table on which the document is placed;
A document table cover that opens and closes with respect to the document table;
Cover open detecting means for detecting an open / closed state of the document table cover;
A document size detecting means for detecting a size of the document on the document table in a semi-closed state when the document table cover is shifted from an open state to a closed state;
Control means for switching between the normal mode and the power saving mode according to a predetermined condition ;
Measuring means for measuring the speed at which the platen cover is closed ,
The control means includes
Wherein when the normal mode shift to the power saving mode, if prior SL document cover is open, based on the speed of the history in which the platen cover, which is measured by the measuring means is closed, the normal the controls whether Luke not to continue the power supply to the document size detection means in mode, when the document cover is in a closed state to stop the power supply to the document size detection means,
When the supply of power to the document size detection unit is stopped in the power saving mode when returning from the power saving mode to the normal mode due to a change in the open / close state of the document table cover, the power supply is resumed. image reading apparatus characterized by to. An integrated circuit that is connected to the control means and the document size detection means and constructs a logic circuit therein based on circuit information;
The control means includes
In the normal mode, the integrated circuit is configured to construct a normal time circuit for executing image reading processing,
In the transition from the normal mode to the power saving mode, the integrated circuit is configured to construct a power saving time circuit having a circuit size smaller than the normal time circuit, which communicates with the document size detecting means.
When the supply of power to the document size detection unit is stopped in the power saving mode when returning from the power saving mode to the normal mode due to a change in the open / close state of the document table cover, the power supply is resumed. The image reading apparatus according to claim 1 , wherein the document size detecting unit is activated by the power saving circuit .