Image reader

Abstract

To reduce occurrence of an intermittent operation during reading image data of a document, even when a size of a storage unit is smaller than image data of one conveyance medium of a maximum size in read settings.SOLUTION: An image reader includes: a conveyance unit 102 which conveys a document S; an image reading unit 103 which reads an image on the document S; a storage unit 104 which stores the image read by the image reading unit 103; and a monitoring unit 107 which monitors the space used in the storage unit 104, interrupts, when the used space becomes equal to or larger than a first threshold, the conveyance unit 102 conveying the document, and restarting, when the used space becomes equal to or smaller than a second threshold, the conveyance unit 102 conveying the document. The first threshold and the second threshold for a section in which the image reading unit 103 is reading an image are different from those for a section in which the image reading unit 103 is not reading an image.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an image reading device. [Background technology]

[0002] Currently, image reading devices equipped with an automatic document feeder (ADF: Auto Document Feeder) are widely available, such as scanners, copiers, and facsimile machines. These image reading devices have the function of transporting documents one by one from a batch into the image reading device and continuously outputting the electronic data of each document.

[0003] Furthermore, in recent years, with the spread of wireless networks and mobile devices, the speed at which image reading devices output image data to host devices is often unstable. In this case, image data accumulates in the image reading device, the memory in the image reading device becomes full, and it becomes necessary to temporarily stop reading the document. However, if the transport of the document and reading are interrupted while reading the image data of the document, there is a possibility that abnormalities will occur in the image data, such as color shifts and stretching, at the point where reading was interrupted.

[0004] Against this background, a technology has been proposed for temporarily stopping image reading when the memory in a scanner or copier becomes full in the middle of scanning an original, as in Patent Document 1. Patent Document 1 describes a function that operates intermittently between sheets until there is enough free space to store the image data of the next sheet of paper. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-052352 Summary of the Invention [Problem to be solved by the invention]

[0006] The image reading device of Patent Document 1 is premised on the memory size being a size that can store image data for one sheet of a conveyed medium of the maximum size in the reading settings.

[0007] The present invention provides a technology that can reduce the occurrence of intermittent operations during reading of image data of a document, even when the memory size is smaller than the size that can accommodate image data of one sheet of a conveyed medium of the maximum size in the reading settings. [Means for solving the problem]

[0008] In view of the above, an image reading device according to the present invention comprises: A conveying unit that conveys the document; an image reading unit that reads an image of the document; a storage unit that stores the image read by the image reading unit; a monitoring unit that monitors a usage capacity of the storage unit, and when the usage capacity becomes equal to or greater than a first threshold, suspends the transport of the document by the transport unit, and when the usage capacity becomes equal to or less than a second threshold, resumes the transport of the document by the transport unit; having The first threshold value or the second threshold value is different between a section in which the image reading unit is reading an image and a section in which the image reading unit is not reading an image. Effect of the Invention

[0009] According to the present invention, it is possible to reduce the frequency of occurrence of intermittent operations during image reading of one document. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing the configuration of an image reading apparatus according to an embodiment of the present invention; [Diagram 2] Cross-sectional view of an image reading device [Diagram 3] FIG. 1 is a diagram for explaining an intermittent operation of an image reading device 100 according to a conventional technique. [Figure 4] FIG. 1 is a diagram for explaining an intermittent operation of the image reading device 100 according to the first embodiment of the present invention. [Diagram 5]FIG. 1 is a diagram for explaining a sheet intermittent operation threshold according to a second embodiment of the present invention; [Figure 6] FIG. 2 is a diagram for explaining a sheet intermittent operation threshold according to a second embodiment of the present invention; [Figure 7] FIG. 3 is a diagram for explaining a sheet intermittent operation threshold according to the second embodiment of the present invention; [Figure 8] FIG. 11 is a diagram illustrating an intermittent operation of an image reading device 100 according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] <<First embodiment>> <Outline of the image reading device> Fig. 1 is a configuration diagram of an image reading device according to an embodiment of the present invention. An example of the main hardware configuration of an image reading device 100 according to this embodiment is shown using Fig. 1. In the following explanation, the same components are given the same reference numbers and their explanation is omitted. Note that the configuration shown in Fig. 1 is one example and may include other parts.

[0012] The CPU 101 uses computer programs and data stored in a storage unit 104 to perform overall control of the operations of each component of the image reading device 100 .

[0013] The conveying unit 102 is a means for conveying a document, which is a conveying medium, into the image reading device 100 using a method described later with reference to FIG. 2, and discharging the document outside the housing.

[0014] The image reading unit 103 obtains an image of the document conveyed by the conveying unit 102 in a manner described later with reference to FIG.

[0015] The storage unit 104 functions as a work area used by the CPU 101 when executing various processes, and as a storage area for temporarily storing images read by the image reading unit, etc. The storage unit 104 is composed of a storage medium such as a RAM (Random Access Memory) or a ROM (Read Only Memory). The entire area of ​​the storage unit 104 does not necessarily need to be installed inside the housing. For example, a storage medium area of ​​an external device (such as a USB memory) connected to the image reading device 100 may be used as part of the storage area to store images, etc.

[0016] The detector 105 detects the position of the document conveyed into the housing by the conveyor 102 using a method that will be described later with reference to FIG.

[0017] The interface unit 106 is an interface that performs information communication with an external device. If the external device is a PC (Personal Computer), the interface unit 106 may be, for example, a Universal Serial Bus (USB) interface or a Small Computer System Interface (SCSI). In addition to such a wired communication interface, the interface unit 106 may be configured to employ a wireless communication interface, or may include interfaces for both wired communication and wireless communication.

[0018] A monitor unit 107 monitors the free space of the storage unit 104, and based on the monitor result, the CPU 101 instructs the transport unit 102 to stop transport and restart transport, thereby performing intermittent operation.

[0019] <Description of the conveying unit and image reading unit> The conveying unit and the image reading unit of the image reading device according to this embodiment will be described with reference to FIG.

[0020] The image reading device 100 is a device that conveys one or more conveying media S loaded on a loading platform 1 one by one along a route RT within the device, reads the image on the medium, and discharges the medium onto a discharge tray 2. The conveying media S to be read are, for example, sheets such as office paper, checks, cards, etc., and may be thick or thin sheets. Examples of cards include insurance cards, driver's licenses, and credit cards. The conveying media S also includes booklets such as passports.

[0021] Next, the conveying unit 102 will be described. The image reading device 100 is provided with a first conveying unit 10 as a feeding mechanism that feeds the conveying medium S along a path RT. In this embodiment, the first conveying unit 10 includes a feed roller 11 and a separation roller 12 arranged opposite the feed roller 11, and conveys the conveying medium S on the mounting table 1 one by one in a conveying direction D1. A driving force is transmitted to the feed roller 11 from a driving unit 3 such as a motor via a transmission unit 4, and the feed roller 11 is driven to rotate counterclockwise in the figure (in a direction in which the conveying medium S is conveyed along the path RT). The transmission unit 4 is, for example, an electromagnetic clutch, and connects and disconnects the driving force from the driving unit 3 to the feed roller 11.

[0022] In this embodiment, for example, the transmission unit 4 that connects the drive unit 3 and the feed roller 11 is in a state in which the driving force is normally transmitted, and the driving force is cut off when the transport medium S is fed in the reverse direction. When the transmission of the driving force is cut off by the transmission unit 4, the feed roller 11 is in a state in which it can rotate freely. Note that such a transmission unit 4 does not need to be provided when the feed roller 11 is driven in only one direction.

[0023] The separation roller 12, which is disposed opposite the feed roller 11, is a roller for separating the transport media S one by one, and is in contact with the feed roller 11 with a constant pressure. To ensure this state of contact, the separation roller 12 is provided so as to be swingable and configured so as to be biased toward the feed roller 11. A driving force is transmitted to the separation roller 12 from the drive unit 3 via a torque limiter 12a, and the separation roller 12 is driven to rotate in the direction of the solid arrow (the same as the feed roller 11, counterclockwise in the figure).

[0024] Since the transmission of driving force is restricted by the torque limiter 12a, the separation roller 12 rotates in a direction (indicated by a dashed arrow) that rotates together with the feed roller 11 when in contact with the feed roller 11. As a result, when multiple conveying media S are conveyed to the pressure contact portion between the feed roller 11 and the separation roller 12, two or more conveying media S except for one are blocked so as not to be conveyed downstream.

[0025] In this embodiment, the separation mechanism is composed of the separation roller 12 and the feed roller 11, but such a separation mechanism is not necessarily provided, and any feed mechanism that sequentially feeds the transport medium S one by one to the path RT will suffice. In addition, when a separation mechanism is provided, instead of a configuration such as the separation roller 12, a separation pad that applies friction to the transport medium S may be pressed against the feed roller 11 to provide a similar separation function.

[0026] The second conveying section 20, which serves as a conveying mechanism located downstream of the first conveying section 10 in the conveying direction, includes a drive roller 21 and a driven roller 22 driven by the drive roller 21, and conveys the conveyed medium S conveyed from the first conveying section 10 to the downstream side. A driving force is transmitted to the drive roller 21 from a drive unit 3 such as a motor, and the drive roller 21 is driven to rotate in the direction of the arrow in the figure. The driven roller 22 is pressed against the drive roller 21 with a constant pressure, and rotates together with the drive roller 21. The driven roller 22 may be configured to be biased against the drive roller 21 by a biasing unit (not shown) such as a spring.

[0027] The third conveying section 30, which is located downstream in the conveying direction from the second conveying section 20, includes a driving roller 31 and a driven roller 32 driven by the driving roller 31, and conveys the conveyed medium S conveyed from the second conveying section 20 to the discharge tray 2. In other words, the third conveying section 30 functions as a discharge mechanism. A driving force is transmitted from a driving section 3 such as a motor to the driving roller 31, and the driving roller 31 is rotated in the direction of the arrow in the figure. The driven roller 32 is pressed against the driving roller 31 with a constant pressure, and rotates with the driving roller 31. The driven roller 32 may be configured to be biased against the driving roller 31 by a biasing unit such as a spring. The conveying section 102 is configured by the first conveying section 10, the second conveying section 20, and the third conveying section 30, which are the feeding sections as described above, but is not limited to this.

[0028] The double-feed detection sensor 40 disposed between the first conveying section 10 and the second conveying section 20 is an example of a detection sensor (a sensor that detects the behavior or state of sheets) for detecting when conveying media S such as paper have come into close contact with each other due to static electricity or the like and passed through the first conveying section 10 (i.e., when there is a double-feed state in which the conveying media S are conveyed overlapping each other). Various types of double-feed detection sensor 40 can be used, but in this embodiment, it is an ultrasonic sensor that includes an ultrasonic transmitter 41 and a receiver 42, and detects double-feeding based on the principle that the attenuation of ultrasonic waves passing through conveying media S such as paper differs between when the conveying media S are conveyed overlappingly and when they are conveyed one by one. In this embodiment, the double feed detection sensor 40 may be omitted.

[0029] Next, the medium detection sensor 50 will be described as the detection unit 105. The medium detection sensor 50, which is disposed downstream of the double feed detection sensor 40 in the conveying direction, is an example of an upstream detection sensor (a sensor that detects the behavior or state of a sheet) disposed upstream of the second conveying unit 20 and downstream of the first conveying unit 10, and detects the position of the conveyed medium S conveyed by the first conveying unit 10, more specifically, whether or not the end of the conveyed medium S has reached or passed the detection position of the medium detection sensor 50. Various types of medium detection sensor 50 can be used, but in this embodiment, it is an optical sensor that includes a light emitting unit 51 and a light receiving unit 52, and detects the conveyed medium S on the principle that the received light intensity (received light amount) changes when the conveyed medium S reaches or passes through it.

[0030] In this embodiment, the medium detection sensor 50 is provided downstream of and in the vicinity of the double feed detection sensor 40 so that when the leading edge of the conveyed medium S is detected by the medium detection sensor 50, the conveyed medium S has reached a position where double feed can be detected by the double feed detection sensor 40. Note that the medium detection sensor 50 is not limited to the optical sensor described above, and may be, for example, a sensor (such as an image sensor) capable of detecting the end of the conveyed medium S, or a lever-type sensor or ultrasonic sensor protruding into the path RT.

[0031] As the detection unit 105, a medium detection sensor 60 separate from the medium detection sensor 50 will be described. The medium detection sensor 60 is an example of a downstream detection sensor arranged upstream of the image reading units 70a and 70b and downstream of the second conveying unit 20, and detects the position of the conveyed medium S conveyed by the second conveying unit 20. Various types of medium detection sensor 60 can be used, but in this embodiment, it is an optical sensor similar to the medium detection sensor 50, and includes a light emitting unit 61 and a light receiving unit 62, and detects the conveyed medium S based on the principle that the received light intensity (received light amount) changes when the conveyed medium S arrives or passes through. In this embodiment, the medium detection sensors 50 and 60 are arranged on the upstream side and downstream side of the second conveying unit 20 in the conveying direction, respectively, but only one of them may be used.

[0032] Next, the image reading units 70a and 70b as the image reading section will be described. The image reading units 70a and 70b, which are located downstream of the media detection sensor 60, for example, optically scan and convert the image into an electrical signal to read it as an image, and are equipped with a light source such as an LED, an image sensor, a lens array, etc. In the case of this embodiment, the image reading units 70a and 70b are arranged on both sides of the path RT, and read the front and back sides of the transported medium S. However, as a configuration in which one is arranged on only one side of the path RT and only one side of the transported medium S is read, In this embodiment, the image reading units 70a and 70b are arranged opposite each other on either side of the path RT, but they may be arranged with an interval therebetween in the direction of the path RT, for example.

[0033] The basic operation of the image reading device 100 will be described. When the control unit 8 receives an instruction to start image reading, the control unit 8 starts driving the first conveying unit 10, the second conveying unit 20, and the third conveying unit 30 by the driving unit 3. The conveying media S loaded on the mounting table 1 are conveyed one by one starting from the conveying media S located at the bottom (the side closest to the mounting table 1).

[0034] The control unit 8 starts image reading of the conveyed medium S conveyed by the second conveying unit 20 by the image reading units 70a and 70b at a timing based on the detection result of the medium detection sensor 60, stores the read images in the storage unit 104, and then sequentially transmits the images to the outside via the interface unit 106. The conveyed medium S after image reading is discharged to the discharge tray 2 by the third conveying unit 30.

[0035] In the above-described method, the image reading device 100 includes a conveying unit 102 that conveys the medium S to be conveyed and an image reading unit 103 that reads the image of the medium S to be conveyed.

[0036] <Description of memory full state, memory full state release judgment and intermittent operation> The method of determining whether the memory is full or not and the method of determining whether the memory is released from the full state in this embodiment will be described below. The method and the process of temporarily suspending image reading of a document stack (hereinafter, referred to as intermittent operation) will be described below.

[0037] The medium S is separated one by one by the method described in FIG. 2 and fed into the transport path RT in the direction of the arrow. At this time, the nth medium S is fed as S n , the n+1th transport medium is S n+1 Let us assume that.

[0038] 3 and 4 show the conveying medium S (for example, three conveying media S 1 , S 2 , S 3 3 is a time chart showing a schematic representation of the memory usage of the storage unit 104, the operation of the image reading unit 103, and the operation of the conveying unit 102 when reading an image of a document (image), as shown in FIG. 3. FIG. 3 shows the operation of the prior art, and FIG. 4 shows the operation of the first embodiment of the present invention.

[0039] 3 and 4, the free area M1 represents the free area of ​​the memory of the storage unit 104, and the colored used area M2 represents the used area in the memory of the storage unit 104. There are also two types of thresholds for the used area of ​​this memory, a first threshold H and a second threshold L in FIG. 3, and a first threshold H or IH, and a second threshold L or IL in FIG. 4.

[0040] First, the operation of the conventional technology will be described with reference to FIG.

[0041] Upon receiving the instruction to start image reading, the conveying unit 102 starts the feeding operation of the conveyed medium S, and the image reading unit 103 reads the conveyed medium S at a timing based on the detection result of the medium detection sensor 60. 1 Image reading is started (T001), and the read image data is stored in the storage unit 104.

[0042] When the monitoring unit 107 detects that the used area of ​​the storage unit 104 has reached or exceeded the first threshold value H, it determines that the memory is full and instructs the transport unit 102 to stop transporting. As a result of the transport being stopped, the image reading unit 103 interrupts reading (T002).

[0043] Thereafter, the free space in the storage unit 104 increases as the images are sequentially sent to the outside via the interface unit 106, and when the monitoring unit 107 detects that the used capacity of the storage unit 104 has fallen below the second threshold value L, it determines that the memory full state has been cleared and instructs the conveying unit 102 to resume conveying.As conveying is resumed, the image reading unit 103 resumes reading (T003).

[0044] After that, the image reading unit 103 reads the conveyed medium S 1 After reading the entire area of ​​the transport medium S 1 Image reading is then terminated (T004).

[0045] Next, at a timing based on the detection result of the medium detection sensor 60, the image reading unit 103 reads the conveyed medium S. 2 The image reading of the conveyed medium S is started (T005), and the image data is stored in the storage unit 104. 1 Since the image data of the transport medium S remains, 1 Compared to the reading of the first image, the monitoring unit 107 detects that the usage capacity of the storage unit 104 has reached or exceeded the first threshold value H earlier, determines that the memory is full, and instructs the conveying unit 102 to stop conveying. As a result of the conveying being stopped, the image reading unit 103 interrupts reading (T006).

[0046] Thereafter, the free space increases as images are sequentially sent to the outside via the interface unit 106, and when the monitoring unit 107 detects that the used capacity of the storage unit 104 has fallen below the second threshold value L, it determines that the memory full state has been cleared and instructs the conveying unit 102 to resume conveying.As conveying is resumed, the image reading unit 103 resumes reading (T007).

[0047] Since the first intermittent operation occurred early, the transport medium S 2 Before the image reading is completed, the monitoring unit 107 again detects that the used capacity of the storage unit 104 has reached or exceeded the first threshold value H, determines that the memory is full, and instructs the transport unit 102 to stop transport. As a result of the transport being stopped, the image reading unit 103 interrupts reading (T008).

[0048] Thereafter, the free space increases as images are sequentially sent to the outside via the interface unit 106, and when the monitoring unit 107 detects that the used capacity of the storage unit 104 has fallen below the second threshold value L, it determines that the memory full state has been cleared and instructs the conveying unit 102 to resume conveying.As conveying is resumed, the image reading unit 103 resumes reading (T009).

[0049] After that, the image reading unit 103 reads the conveyed medium S 2 After reading the entire area of ​​the transport medium S 2 Then, image reading is terminated (T010).

[0050] Hereafter, the transport medium S 3 Regarding reading of the transport medium S 2 For the same reason as for the transport medium S 1 The number of occurrences of intermittent operation increases. 3 The entire area of ​​the transport medium S is read. 3 After completing the image reading of the conveyed medium S 3 When the medium S is conveyed until it is discharged, the conveying unit 102 stops conveying the medium S. 3 When all of the image data has been read out from the memory of the storage unit 104, the image reading operation ends.

[0051] Next, the operation of the first embodiment of the present invention will be described with reference to FIG.

[0052] Upon receiving the instruction to start image reading, the conveying unit 102 starts the feeding operation of the conveyed medium S, and the image reading unit 103 reads the conveyed medium S at a timing based on the detection result of the medium detection sensor 60. 1 The image reading of the transport medium S is started (T101), and the read image data is stored in the storage unit 104. 1 When the reading of the image reading unit 103 starts, the monitoring unit 107 sets the first threshold value H and the second threshold value L as threshold values ​​during reading. Note that, at least in this embodiment, the storage capacity (size) of the storage unit 104 is set to the maximum size of the conveyed medium S that can be set in the reading setting of the image reading unit 103. 1 It is smaller than the size that can hold one page of image data.

[0053] When the monitoring unit 107 detects that the used capacity of the storage unit 104 has reached or exceeded the first threshold H, it determines that the memory is full, instructs the transport unit 102 to stop transporting, and the image reading unit 103 interrupts reading accordingly (T102).

[0054] After that, by sequentially transmitting images to the outside via the interface unit 106, the free capacity increases. When the monitoring unit 107 detects that the used capacity of the storage unit 104 has become equal to or less than the second threshold L, it determines that the memory full state is released, instructs the transport unit 102 to resume transporting, and the image reading unit 103 resumes reading accordingly (T103).

[0055] After that, the image reading unit 103 1 reads the entire area of the transport medium S 1 and then ends the image reading of the transport medium S (T104).

[0056] Upon the completion of reading of the transport medium S 1 the monitoring unit 107 sets the first threshold IH and the second threshold IL to be used as the thresholds for between media. In this embodiment, the magnitude relationship of each threshold is IL < IH < L < H. When it is detected at the time T104 when the reading of the transport medium S 1 is completed (the time when the thresholds for between media are set) that the used capacity of the storage unit 104 has reached or exceeded the first threshold IH, it determines that the memory is full and instructs the transport unit 102 to stop transporting.

[0057] After that, by sequentially transmitting images to the outside via the interface unit 106, the free capacity increases. When the monitoring unit 107 detects that the used capacity of the storage unit 104 has become equal to or less than the second threshold IL and determines that the memory full state is released, it instructs the transport unit 102 to resume transporting (T105).

[0058] Subsequently, at the timing based on the detection result of the medium detection sensor 60, the image reading unit 103 starts reading the image of the transport medium S 2 and stores the image data in the storage unit. The transport medium S 2When image reading starts, the monitoring unit 107 changes the threshold value during reading to use the first threshold value H and the second threshold value L. When the monitoring unit 107 detects that the used capacity of the storage unit 104 has become equal to or greater than the first threshold value H, it determines that the memory is full and instructs the transport unit 102 to stop transport. As the transport is stopped, the image reading unit 103 interrupts reading (T107).

[0059] Thereafter, the free space increases by sequentially transmitting images to the outside via the interface unit 106, and when the monitoring unit 107 detects that the used capacity of the storage unit 104 has become equal to or less than the second threshold value L and determines that the memory full state has been released, it instructs the conveying unit 102 to resume conveying, and the image reading unit 103 resumes reading in response to the resumption of conveying (T108). 2 After reading the entire area of ​​the transport medium S 2 Then, image reading is completed (T109).

[0060] Transport medium S 2 When the reading of the first medium is completed, the monitoring unit 107 sets the first threshold value IH and the second threshold value IL as the threshold value for the gap between media. At this point, the monitoring unit 107 detects that the used capacity of the storage unit 104 has fallen to or below the first threshold value IH, determines that the memory is full, and instructs the transport unit 102 to stop transporting.

[0061] Thereafter, the free space increases as images are sequentially sent to the outside via the interface unit 106, and when the monitoring unit 107 detects that the used capacity of the storage unit 104 has fallen below the second threshold value IL and determines that the memory full state has been lifted, it instructs the transport unit 102 to resume transport (T110).

[0062] Next, at a timing based on the detection result of the medium detection sensor 60, the image reading unit 103 reads the conveyed medium S 3 Then, image reading of the conveyed medium S is started (T111), and the image data is stored in the storage unit 104. 3 When image reading is started, the monitoring unit 107 sets the first threshold value H and the second threshold value L to be used as threshold values ​​during reading.

[0063] When the monitoring unit 107 detects that the used capacity of the storage unit 104 has reached or exceeded the first threshold H, it determines that the memory is full and instructs the transport unit 102 to stop transporting. As a result of the transport being stopped, the image reading unit 103 stops reading (T112).

[0064] Thereafter, the free space increases by sequentially transmitting images to the outside via the interface unit 106, and when the monitoring unit 107 detects that the used capacity of the storage unit 104 has reached or exceeded the second threshold value L and determines that the memory full state has been released, it instructs the conveying unit 102 to resume conveying, and the image reading unit 103 resumes reading in response to the resumption of conveying (T113). 3 After reading the entire area of ​​the transport medium S 3 Then, image reading is completed (T114).

[0065] Transport medium S 3 When the reading of the first medium is completed, the monitoring unit 107 sets the first threshold value IH and the second threshold value IL as the threshold value for the gap between the media. At this point, the monitoring unit 107 detects that the used capacity of the storage unit 104 has reached or exceeded the first threshold value IH, determines that the memory is full, and instructs the transport unit 102 to stop transporting.

[0066] Thereafter, the free space increases by sequentially transmitting images to the outside via the interface unit 106, and when the monitoring unit 107 detects that the used capacity of the storage unit 104 has fallen below the second threshold value IL and determines that the memory full state has been lifted, it instructs the transport unit 102 to resume transport (T115).

[0067] Then, the transport medium S 3 When the medium S is conveyed until it is discharged, the conveying unit 102 stops conveying (T116). 3 When all of the image data has been read out from the memory of the storage unit 104, the image reading operation ends.

[0068] In this embodiment, the function of the monitor unit 107 is realized by the CPU 101 checking the memory state of the storage unit 104 at the opportunity of a timer interrupt, but other interrupts or other timings that occur regularly may also be used.

[0069] As described above, according to the operation of the present invention, the conveying medium S n From the end of image reading of the transported medium S n+1 In the section where no image is read between the start of image reading, the first threshold value is set to a threshold value IH between media that has more free space than the threshold value H during image reading, thereby inducing intermittent operation, and the second threshold value is set to a threshold value IL between media that has more free space than the threshold value L during image reading, thereby inducing intermittent operation. n+1 By increasing the free space of the storage unit 104 at the time of starting image reading of the conveyed medium S n+1 The frequency of occurrence of intermittent operations during image reading can be reduced.

[0070] In this embodiment, the first and second thresholds are set in the section where the image is not read to determine whether to stop or resume the transport, but a single threshold may be used to determine whether to stop or resume the transport. n The conveyance may be resumed when all the image data has been read out from the memory of the storage unit 104.

[0071] <<Second embodiment>> Next, the operation of the second embodiment of the present invention will be described.

[0072] In the second embodiment, the conveying medium S n When reading an image of the conveying medium S, the speed at which the image reading unit 103 stores the image data in the storage unit 104 exceeds the speed at which the image data is transmitted to the outside via the interface unit 106, resulting in an increase in the memory usage amount Δn of the storage unit 104. n The memory usage MS of the storage unit 104 at the time of starting reading n and the transport medium S n Memory usage ME of the storage unit 104 at the end of reading n and the transport medium S n Number of intermittent operations during reading I n The transport medium S n and S. n+1A single intermittent operation threshold IT n This allows the conveying medium S n+1 Memory usage at the start of reading MS n+1 The transport medium S n+1 By setting the number of intermittent operations during image reading to the maximum value among the values ​​that can be minimized, the number of intermittent operations can be minimized while the conveyed medium S n and S. n+1 The intermittent operation time between sheets is minimized.

[0073] Intermittent operation threshold IT n In calculating the speed at which the image data read by the image reading unit 103 is stored in the storage unit 104 when reading an image, the speed is determined by the speed of the conveying medium S n and S. n+1 The speed at which the image is transmitted to the outside via the interface unit 106 is also the same as the speed at which the image is transmitted to the outside via the transport medium S. n and S. n+1 The calculation is performed assuming that they are identical.

[0074] Transport medium S n The increase in memory usage Δn of the storage unit 104 when reading the transport medium S n The memory usage MS of the storage unit 104 at the time of starting reading n and transport medium S n The memory usage of the storage unit 104 at the end of reading n and the transport medium S n Number of intermittent operations during reading I n The increase in memory usage Δn is calculated by the following formula using the first threshold H and the second threshold L of the intermittent operation during image reading. n This refers to the difference between the total amount of data written to memory from the start of reading to the end of reading and the total amount of data transmitted to the outside via interface unit 106, and includes not only the simple change in memory usage before and after reading, but also the decrease in usage due to intermittent operation. Δn=ME n -MS n +(I n ×(HL))

[0075] As shown in FIG. 5, when the conveyance medium S n reaches the end of reading, if H > Δn and ME n + Δn < H, even if it is assumed that the memory usage amount MS of the storage unit 104 at the start of reading of the conveyance medium S n+1 is equal to the memory usage amount ME of the storage unit 104 at the end of reading of the conveyance medium S n+1 , since MS n + Δn < H and the memory usage amount of the storage unit 104 does not exceed the first threshold value H even if it increases by Δn during the image reading of the conveyance medium S n , it is determined that the intermittent operation is not performed, and the intermittent operation between the conveyance media S n+1 and S n+1 is not performed between the sheets. n and S n+1 No intermittent operation is performed between the sheets of S.

[0076] On the other hand, as shown in FIG. 6, when the conveyance medium S n reaches the end of reading, if H > Δn and H ≤ ME n + Δ, assuming that the memory usage amount MS of the storage unit 104 at the start of reading of the conveyance medium S n+1 is equal to the memory usage amount ME of the storage unit 104 at the end of reading of the conveyance medium S n+1 , then H ≤ MS n + Δn, and when the memory usage amount of the storage unit 104 increases by Δn during the image reading of the conveyance medium S n , it is determined that the intermittent operation is performed when the memory usage amount exceeds the first threshold value H, and the intermittent operation threshold value IT n+1 obtained by the following formula is used to perform the intermittent operation between the conveyance media S n+1 and S n1 . n and S n+1 Perform intermittent operation between the sheets. IT n1 = H - Δn

[0077] When the memory usage amount MS of the storage unit 104 at the start of reading of the conveyance medium S n+1 is equal to this IT n+1 , when the memory usage amount of the storage unit 104 increases by Δn during the image reading of the conveyance medium S n1 , the memory usage amount ME at the end of the image reading of the conveyance medium S n+1 n+1 ​​n+1 When the first threshold H of the intermittent operation during image reading is reached, the intermittent operation occurs. However, this is the worst case scenario. In reality, however, the conveyed medium S n From the end of image reading of the transported medium S n+1 In order to transmit images to the outside through the interface unit 106 during the period until the medium S is conveyed to the position where image reading starts, n+1 The memory usage MS of the storage unit 104 at the time of starting reading n+1 IT n1 Even if the memory usage increases by Δn, the first threshold H for intermittent operation is not reached, and intermittent operation is not performed. n1 may be subtracted by a certain margin.

[0078] Next, as shown in FIG. n When reading is completed, if H≦Δn, the conveyed medium S n+1 When the memory usage of the storage unit 104 increases by Δn due to image reading of the conveyed medium S n+1 The memory usage MS of the storage unit 104 at the time of starting reading n+1 Even if the first threshold H is 0, the intermittent operation is performed in the middle. n+1 In order to minimize the number of intermittent operations during image scanning, set the intermittent operation threshold IT n2 and use it to calculate the transport medium S n and S. n+1 The intermittent operation is performed between the sheets.

[0079] First, the transport medium S n+1 Number of intermittent occurrences at I n+1 The memory usage MS of the storage unit 104 at the start of image reading is calculated. n+1 Since the number of intermittent operations is the smallest when is 0, n+1 = 0 and the number of intermittent I n+1 The minimum value of Min(I n+1 ) can be calculated using the following formula: Min(I n+1 )=(Δn-L) / (HL)

[0080] Also, Min(I n+1 ) with transport medium S n+1 Memory usage at the end of image scanning n+1 is expressed by the following formula. ME n+1 =(Δn-Min(I n+1 )×(HL))+MS n+1 =L+MS n+1

[0081] That is, Min(I n+1 ) in ME n+1 The value is MS n+1 It increases or decreases depending on the value of ME n+1 When the first threshold H of intermittent operation is reached, the number of intermittent operations is no longer the minimum. Therefore, the intermittent operation threshold IT n2 By conveying medium S n and S. n+1 By performing intermittent operation between sheets of paper, n+1 does not reach the first threshold H of the intermittent operation. IT n2 =H-(Δn-Min(I n+1 )×(HL))

[0082] Transport medium S n+1 The memory usage MS of the storage unit 104 at the time of starting reading n+1 This IT n2 If it is equal to ME n+1 When the first threshold H of the intermittent operation is reached, the intermittent operation occurs. n+1 The memory usage MS of the storage unit 104 at the time of starting reading n+1 IT n2 Even if memory usage increases by Δn, n+1 does not reach the first threshold H of intermittent operation, and intermittent operation is not performed. Also, taking into consideration fluctuations in the speed at which images are transmitted to the outside via the interface unit 106, the intermittent operation threshold IT n2 may be subtracted by a certain margin.

[0083] The image reading operation of the second embodiment of the present invention will be described with reference to FIG. 8. FIG. 8 shows the image reading operation of the conveyed medium S (three conveyed media S as an example) in the second embodiment of the present invention. 1 , S 2 , S 3 10 is a time chart showing a schematic representation of the memory usage of the storage unit 104, the operation of the image reading unit, and the operation of the conveying unit when reading an image corresponding to the document.

[0084] Upon receiving the instruction to start image reading, the conveying unit 102 starts the feeding operation of the conveyed medium S, and the image reading unit 103 reads the conveyed medium S at a timing based on the detection result of the medium detection sensor 60. 1 Image reading is started (T201), and the read image data is stored in the storage unit.

[0085] Transport medium S 1 When the reading of the medium S starts, the monitoring unit 107 1 Memory usage at the start of reading (MS 1 ) and the transport medium S 1 Number of intermittent operations during reading (I 1 ) is set to 0, and the values ​​of the first threshold and the second threshold are set to H and L.

[0086] When the monitoring unit 107 detects that the capacity of the storage unit 104 is equal to or greater than the first threshold H, it is determined that the memory is full and the transport medium S 1 Number of intermittent operations during reading (I 1 ) is counted up, and the transport unit 102 is instructed to stop transport. With the transport being stopped, the image reading unit 103 interrupts reading (T202).

[0087] Thereafter, the free space increases by sequentially transmitting images to the outside via the interface unit 106, and when the monitoring unit 107 detects that the used capacity of the storage unit 104 has become equal to or less than the second threshold value L, it determines that the memory full state has been released and instructs the conveying unit 102 to resume conveying. With the resumption of conveying, the image reading unit 103 resumes reading (T203). 1 After reading the entire area of ​​the transport medium S 1 Then, image reading is completed (T204).

[0088] Transport medium S 1 When the reading of the medium S is completed, the monitoring unit 107 1 Memory usage at the end of reading ME 1 After storing the above, the necessity of changing the threshold value for the intermittent operation in the section where the image is not read between the sheets and the threshold value if necessary are calculated.

[0089] First, using the above formula, the conveying medium S 1 Calculate the increase Δ1 in the memory usage of the storage unit 104 when reading. H>Δ1 and H>ME 1 In the case of +Δ1, the transport medium S 1 and S. 2 It is determined that intermittent operation between sheets is unnecessary, and the values ​​of the first threshold and the second threshold are left as H and L.

[0090] Otherwise, the transport medium S 1 and S. 2 It is judged that intermittent operation is necessary between the sheets of transport medium S. 1 and S. 2 A single intermittent operation threshold IT 1 is calculated based on the above formula and set as the threshold value. 1 When the memory capacity of the storage unit 104 reaches H-IT, the storage unit 104 judges that the memory is full and instructs the transport unit 102 to stop transporting. After that, the free space increases as images are sequentially sent to the outside via the interface unit 106. The monitor unit 107 detects that the used space of the storage unit 104 reaches H-IT 1 When it is detected that the memory full state has been released, the transport unit 102 is instructed to resume transport (T205).

[0091] Next, at a timing based on the detection result of the medium detection sensor 60, the image reading unit 103 reads the conveyed medium S 2 The image reading of the transport medium S is started (T206), and the image data is stored in the storage unit. 2 When image reading of the conveyed medium S starts, the monitor unit 107 2 Memory usage at the start of reading MS 2 and the conveying medium S 2 Number of intermittent operations during reading I2 is set to 0, and the values ​​of the first threshold and the second threshold are set to H and L.

[0092] When the monitoring unit 107 detects that the capacity of the storage unit 104 is equal to or greater than the first threshold H, it is determined that the memory is full and the transport medium S 2 Number of intermittent operations during reading I 2 The counter 104 counts up, and instructs the conveying unit 102 to stop conveying. With the conveying being stopped, the image reading unit 103 stops reading (T207).

[0093] Thereafter, the free space increases by sequentially transmitting images to the outside via the interface unit 106, and when the monitoring unit 107 detects that the used capacity of the storage unit 104 has become equal to or less than the second threshold value L and determines that the memory full state has been released, it instructs the conveying unit 102 to resume conveying, and the image reading unit 103 resumes reading in response to the resumption of conveying (T208). 2 After reading the entire area of ​​the transport medium S 2 Then, image reading is completed (T209).

[0094] Transport medium S 2 When the reading of the medium S is completed, the monitoring unit 107 2 Memory usage at the end of reading ME 2 After storing the above, the necessity of changing the threshold value for the intermittent operation in the section where the image is not read between the sheets and the threshold value if necessary are calculated.

[0095] First, using the above formula, the conveying medium S 2 Calculate the increase Δ2 in the memory usage of the storage unit 104 when reading. H>Δ2 and H>(ME 2 +Δ2), the transport medium S 2 and S. 3 It is determined that intermittent operation between sheets is unnecessary, and the values ​​of the first threshold and the second threshold are left as H and L.

[0096] Otherwise, the transport medium S 2 and S. 3 It is judged that intermittent operation is necessary between the sheets of transport medium S. 2 and S.3 A single intermittent operation threshold IT 2 is calculated based on the above formula and set as the threshold value. 2 When the memory capacity of the storage unit 104 reaches H-IT, the storage unit 104 judges that the memory is full and instructs the transport unit 102 to stop transporting. After that, the free space increases as the images are sequentially sent to the outside via the interface unit 106. The monitor unit 107 detects that the used space of the storage unit 104 reaches H-IT 2 If it is detected that the memory full state has been released, the transport unit 102 is instructed to resume transport (T205).

[0097] Next, at a timing based on the detection result of the medium detection sensor 60, the image reading unit 103 reads the conveyed medium S 3 The image reading of the transport medium S is started (T211), and the image data is stored in the storage unit. 3 When image reading of the conveyed medium S starts, the monitor unit 107 3 Memory usage at the start of reading MS 3 and the conveying medium S 3 Number of intermittent operations during reading I 3 is set to 0, and the values ​​of the first threshold and the second threshold are set to H and L.

[0098] When the monitoring unit 107 detects that the capacity of the storage unit 104 is equal to or greater than the first threshold H, it is determined that the memory is full and the transport medium S 3 Number of intermittent operations during reading I 3 The counter 104 counts up, and instructs the conveying unit 102 to stop conveying. With the conveying being stopped, the image reading unit 103 stops reading (T212).

[0099] Thereafter, the free space increases by sequentially transmitting images to the outside via the interface unit 106, and when the monitoring unit 107 detects that the used capacity of the storage unit 104 has become equal to or less than the second threshold value L and determines that the memory full state has been released, it instructs the conveying unit 102 to resume conveying, and in response to the resumption of conveying, causes the image reading unit 103 to resume reading (T213). 3 After reading the entire area of ​​the transport medium S 3End image scanning (T214)

[0100] Transport medium S 3 When the reading of the medium S is completed, the monitoring unit 107 3 Memory usage at the end of reading ME 3 After storing the above, the necessity to change the threshold value of the intermittent operation in the section where the image is not read between the sheets is calculated, and if necessary, the threshold value is calculated. First, the conveyed medium S is calculated using the above formula. 3 Calculate the increase Δ3 in the memory usage of the storage unit 104 when reading. H>Δ3 and H>ME 3 In the case of +Δ3, the transport medium S 3 It is determined that intermittent operation after reading is unnecessary, and the values ​​of the first threshold and the second threshold are left as H and L.

[0101] Otherwise, the transport medium S 3 It is judged that intermittent operation is necessary after reading, and the conveyed medium S 3 A single intermittent operation threshold value IT for the section where no image is read after reading 3 is calculated based on the above formula and set as the threshold value. 3 When the memory capacity of the storage unit 104 reaches H-IT, the storage unit 104 judges that the memory is full and instructs the transport unit 102 to stop transporting. After that, the free space increases as the images are sequentially sent to the outside via the interface unit 106. The monitor unit 107 detects that the used space of the storage unit 104 reaches H-IT 3 If it is detected that the memory full state has been released, the transport unit 102 is instructed to resume transport (T215). 3 When the medium S is conveyed until it is discharged, the conveying unit 102 stops conveying (T116). 3 When all of the image data has been read out from the memory of the storage unit 104, the image reading operation ends.

[0102] As described above, in the present embodiment, by calculating the increase in memory usage in consideration of the speed at which image data is stored in the storage unit 104 and the speed at which images are transmitted to the outside via the interface unit 106, and determining whether or not to execute the intermittent operation during the paper conveyance, it is possible to reduce the number of times the intermittent operation is executed during the image reading of the conveyance medium.

[0103] The present invention is not limited to the embodiments described above, and various modifications or combinations of the embodiments can be applied without departing from the spirit of the present invention.

[0104] For example, although the magnitude relationship between the first threshold value and the second threshold value has been described, it is not limited to the above-described one, and the relationship of IL < L < IH < H may be established. Also, any of the threshold values may be set to the same value.

Explanation of Signs

[0105] 100 Image reading apparatus 101 CPU 102 Conveying unit 103 Image reading unit 104 Storage unit 105 Detection unit 106 Interface unit S Conveyance medium RT Route D1 Conveying direction 3 Driving unit 10 First conveying unit 11 Feed roller 12 Separation roller 20 Second conveying unit 30 Third conveying unit 50 Medium detection sensor 60 Medium detection sensor 70a Reading unit 70b Reading unit

Claims

1. a conveying unit that conveys the document; an image reading unit that reads an image of the document; a storage unit that stores the image read by the image reading unit; a monitoring unit that monitors a used capacity of the storage unit, suspends the transport of documents by the transport unit when the used capacity becomes equal to or greater than a first threshold, and resumes the transport of documents by the transport unit when the used capacity becomes equal to or less than a second threshold; and An image reading device, characterized in that at least one of the first threshold value and the second threshold value is different between a section in which the image reading unit is reading an image and a section in which the image reading unit is not reading an image.

2. 2. The image reading device according to claim 1, wherein the maximum size of the image data that can be stored in the storage unit is smaller than the maximum size of image data for one document that can be set in the reading setting of the image reading unit.

3. 2. The image reading device according to claim 1, wherein the second threshold value in the section where the image is being read is greater than the first threshold value in the section where the image is not being read.

4. In the section where the image is not read, the first threshold value and the second threshold value are a single threshold value.

4. The image reading device according to claim 3, wherein the value is a value.

5. When reading an image of a first document, the capacity of the storage unit used at the start of image reading and the capacity of the storage unit used at the start of image reading are calculated. the used capacity of the storage unit at the time of completion of reading the document, and the used capacity of the storage unit during reading of the document reaches a first threshold. Based on the number of times that the reading of the first document is completed and the conveyance is interrupted because the reading of the first document is completed, The second threshold value is set in a section where the image is not read. Item 2. The image reading device according to item 1.

Images