JP2020036238A - Image reading device and image reading method - Google Patents

Abstract

To provide an image reading device which uses in common a light source for plural photodetectors for monitoring a document.SOLUTION: The image reading device according to this invention comprises: an image reading unit for reading a document; a placing part for placing plural documents; a transportation unit for transporting a document from the placing part to the image reading unit; a first photodetector for photodetecting the document placed on the placing part; and a second photodetector for photodetecting the document transported to the image reading unit by the transportation unit. The image reading device comprises a light emission unit used in common by the first photodetector and the second photodetector, which are capable of receiving either transmitted light from the light emission unit or light reflected by the document.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image reading device having an image reading function by automatic paper feeding.

  Patent Literature 1 discloses an image reading apparatus having an image reading function by automatic sheet feeding in which a document placed on a sheet feeding tray is continuously read by a contact image sensor. When reading a document continuously, the speed at which the document is transported must be as high as possible. As a result, paper jams due to overlapping documents tend to occur. Therefore, in such an image reading apparatus, the originals on the paper feed tray and the transport path are monitored by a plurality of detecting means.

JP 2002-300345

  As described above, the conventional image reading apparatus has a plurality of detectors for monitoring a document. When photodetectors are used as detectors, a light source is required for each. As a result, in addition to the light source, the number of components such as the driving circuit of the light source and the power cable increases, and the power consumption increases.

  SUMMARY An advantage of some aspects of the invention is to provide an image reading apparatus that commonly uses a light source for a plurality of photodetectors for monitoring a document.

  An image reading apparatus according to the present invention includes an image reading unit that reads a document, a placement unit that can place a plurality of documents, a transport unit that transports the document from the placement unit to the image reading unit, A first photodetector that detects the document placed on the unit by light, and a second photodetector that detects the document conveyed to the image reading unit by the conveyance unit by light, A light-emitting unit commonly used by the first light detector and the second light detector, wherein the first light detector and the second light detector transmit light transmitted from the light-emitting unit; Alternatively, any one of the reflected lights reflected by the document can be received.

  According to the present invention, the number of components such as a light source for detecting a document and a drive circuit of the light source can be reduced, and power consumption can be reduced.

FIG. 2 is a diagram illustrating a system configuration of the image reading apparatus. FIG. 3 is a cross-sectional view of an automatic sheet feeding image reading mechanism. 6 is a flowchart illustrating an image reading operation by automatic paper feeding. FIG. 5 is a diagram illustrating a state in which the presence or absence of a document is detected by a photodetector. It is a flowchart for adjusting the light quantity of the light emitting part with respect to the photodetector in 2nd Embodiment. 10 is a flowchart illustrating an operation of reading an image by automatic sheet feeding that reduces power consumption of a light emitting unit according to the second embodiment.

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

(First embodiment)
(System configuration of image reading device)
FIG. 1 shows a system configuration of a scanner device which is an image reading device of the present invention. Note that the image reading apparatus is not limited to the scanner apparatus, and may be a multifunction peripheral having an image reading function, an image printing function, and an image copying function.

  The image reading apparatus includes a system unit 11 that performs various controls based on an instruction from a user, and an automatic feed image reading mechanism 15 that reads an image while feeding a document. The system unit 11 includes a CPU 110 that issues various control commands, an image processing unit 111 that generates a control signal based on the commands, a drive control unit 112, and a sensor control unit 113. Further, it has a main storage unit 114 and an auxiliary storage unit 115 for storing information, an operation unit 116 for inputting an instruction from a user, and an interface controller (IF controller) 117.

  The CPU 110 is a device that controls, drives, and performs all operations of the image reading apparatus. The image reading apparatus is controlled based on the operation program and setting information of the image reading apparatus stored in the auxiliary storage unit 115. The auxiliary storage unit 115 is a flash memory, an EEPROM, an HDD, or the like. The auxiliary storage unit 115 stores an operation program of the image reading apparatus, setting information of the image reading apparatus, a program for adjusting the amount of current flowing to the light emitting unit 140, setting of reference paper, and the like. The main storage unit 114 is a memory such as an SDRAM, and temporarily stores an operation program of the image reading apparatus and image data.

  The image processing unit 111 controls the image reading module 13 by an analog front-end circuit. The reading of the image of the document is performed in cooperation with the image reading unit 130, the light source (not shown), and the driving unit 12. The image processing unit 111 uses the difference between the input signal from the image reading unit 130 and the reference voltage as an image signal level, samples the image signal level, and converts it into digital data. The image processing unit 111 transmits the read image data to the CPU 110, and the CPU 110 transmits the image data to the information device 2 via the IF controller 117.

  The drive control unit 112 controls the drive unit 12 by a motor driver circuit. The drive unit 12 includes a reading unit drive motor 125 and a transport motor 121. The drive control unit 112 controls a reading unit drive motor 125 that moves the image reading unit 130 and a transport motor 121 that feeds and transports a document placed on a paper feed tray in accordance with an instruction of an operation program received from the CPU 110. Generate a signal. The image reading unit 130 is moved to the document reading position 152 using the reading unit driving motor 125 and the timing belt. The timing belt 122 is also used when reading an image of a document placed on a document table. At this time, the image reading unit 130 reciprocates in the longitudinal direction of the document according to the control signal sent to the reading unit driving motor 125. The transport motor 120 can rotate the pickup roller 123, the transport roller 121, and the paper discharge roller 124 by a gear train. These are the transport units of the present invention.

  The sensor control unit 113 controls the document detection unit 14. The document detection unit 14 includes a light emitting unit 140, a transmitted light detector 141, and a reflected light detector 142. Here, the transmitted light detector 141 detects the presence / absence of a document on the paper feed tray, and the reflected light detector 142 detects the edge of the document on the transport path. For the light emitting unit 140, the sensor control unit 113 performs switching of power supply, adjustment of a current amount, and adjustment of a duty ratio when periodic light emission is performed. For the transmitted light or reflected light photodetector, the power supply is switched and the presence or absence of a document or the edge of the document is detected. Upon receiving a signal regarding detection from the photodetector, the sensor control unit 113 transmits the detected information to the CPU 110.

  The user's instruction is performed from the information device 2 or the operation unit 116. The information device 2 is a desktop PC, a notebook PC, a smartphone, or the like. When the information device 2 is used, transmission of operation data of the image reading device and reception of image data from the image reading device are performed via the IF controller 117. The IF controller 117 is a communication IC such as a USB and a LAN. It should be noted that the present invention is not limited to wired communication, but may be an IC for wireless communication represented by WLAN. The operation unit 116 is a touch panel, a switch, or the like provided in the image reading device. When using the operation unit 116, the user directly operates the image reading device.

(Automatic feed image reading mechanism)
Next, a cross-sectional view of the automatic paper feed image reading mechanism is shown in FIG. The automatic paper feed image reading mechanism 15 mainly includes a paper feed tray 150, transport rollers 121, an image reading unit 130, a light emitting unit 140, a transmitted light detector 141, a reflected light detector 142, and a paper discharge tray 153.

  The paper feed tray 150 is a mounting portion for mounting a document of the image reading device, and can place a plurality of documents. The document placed on the paper feed tray 150 is detected using the light emitting unit 140 and the transmitted light detector 141. The light emitting unit 140 may be a light emitting element such as a visible light or infrared light LED or a laser, and here, a visible light LED is used. Further, the light emitting unit 140 is used as a common light source for the transmitted light detector 141 and the reflected light detector 142. Therefore, the light emitting unit 140 is disposed downstream of the transport path 151. As a result, the distance from the light emitting unit 140 to the transmitted light detector 141 becomes longer, so that the direct light from the light emitting unit 140 is condensed by the condenser lens 145 and reaches the transmitted light detector 141. The material of the condenser lens 145 is glass, plastic, or the like. The light of the light emitting section 140 may be guided using an optical fiber or the like.

  The transmitted light detector 141 is located at a position where it can detect a document on the paper feed tray and can directly receive light from the light emitting unit 140. As the transmitted light detector 141, a photodiode whose resistance changes due to movement of minority carriers in the element that receives light is used. The photodiode functions as a switch that switches between a high resistance state and a low resistance state depending on the amount of light. By using light, a document can be detected with high accuracy regardless of the floating of the document. When the transmitted light reaching the transmitted light detector 141 is blocked by the document, the photodiode has a high resistance. As a result, it can be determined that the document is placed on the paper feed tray 150. Note that the light may be blocked by an indirect method using an actuator that is movable by the weight of the document.

  The document supplied from the paper feed tray 150 is transported to the reading position 152 by the transport rollers 121. The transport roller 121 is driven to rotate by a transport motor 120 adjusted to a rotational speed according to the reading accuracy of the document. The document in the transport path 151 is detected by the reflected light detector 142 (second light detector) between the transport roller 121 and the reading position 152. The reflected light detector 142 is arranged at a position where the reflected light from the document at the detection position can be received. In particular, it is desirable that the angle of incidence from the light emitting unit 140 to the surface of the document and the angle of reflection from the surface of the document to the reflected light detector 142 be the same. The reflected light detector 142 performs document edge detection for detecting not only the presence or absence of a document but also the leading and trailing edges of the document. As the reflected light detector 142, a photodiode whose resistance changes due to movement of minority carriers in the element that receives light is used. When the reflected light detector 142 receives the reflected light from the document, the resistance value decreases. As a result, it can be determined that a document exists at the detection position of the transport path 151.

  The document conveyed by the conveyance rollers 121 is read by the image reading unit 130 at the reading position 152. The reading sensor of the image reading unit 130 is also called a contact image sensor, and is a CMOS linear image sensor. The image reading unit 130 emits light from the light emitting element built in the image reading unit 130 to the document, and converts the input level of the reflected light from the document into a signal. The read document is discharged to the discharge tray 153 using the discharge roller 124.

  In this embodiment, the combination of the transmitted light detector and the reflected light detector is used, but the present invention is not limited to this. That is, the light emitting unit may be arranged inside the transport path 151. For example, FIG. 2B illustrates a configuration in which the light emitting unit 140 is disposed inside the transport path and the light receiving unit is disposed outside the transport path. The document on the paper feed tray 150 and the document on the conveyance path are detected by the transmitted light from the optical fiber 143. If there is a document, the transmitted light reaching the transmitted light detector 141 is blocked, so that the document can be detected. Since the originals have different reflectances, detection sensitivity can be increased by using transmitted light. Next, FIG. 2C shows a configuration in which the light emitting unit 140 and the light receiving unit are arranged inside the transport path. In such a case, the original on the paper feed tray 150 and the original on the transport path can be detected by reflected light. If there is a document, the reflected light detector 142 can receive the reflected light from the document, so that the document can be detected. Since the optical system can be arranged inside the transport path 151, the configuration is compact.

  Further, the light emitting section of the document width detecting sensor may be used in common. The document width detection sensor is arranged on a paper feed tray, and detects the width of a document such as A4 size or postcard size by light. In this case, for example, a light emitting unit or a light source used for document width detection is branched into three by an optical fiber to detect presence / absence of a document in a paper feed tray, edge detection of a document in a transport path, and document width detection in a paper feed tray I do.

(Image reading operation during automatic paper feeding)
The image reading operation at the time of automatic paper feeding according to the present invention will be described with reference to the flowchart in FIG. 3 and the diagram showing the state of document detection in FIG.

  In step S101, image reading by automatic paper feeding is started. The user places a document on the paper feed tray 150. After that, the operation instruction of the image reading by the automatic feeding of the original is performed by using the operation unit 116 or the information device 2.

  In step S102, a document on the paper feed tray 150 is detected. CPU 110 causes light emitting section 140 to emit light. 4A, when there is no original, the transmitted light detector 141 receives the transmitted light from the light emitting unit 140. As a result, the sensor control unit 113 determines that there is no document on the paper feed tray 150. On the other hand, when there is a document as shown in FIG. 4B, the transmitted light detector 141 whose light is blocked by the document cannot receive the transmitted light. As a result, the control unit 113 determines that there is a document on the paper feed tray 150. The sensor control unit 113 repeats the document detection operation until the document can be confirmed.

  In step S103, document feeding is started. The pickup roller 123 and the transfer roller 121 are driven to rotate by the transfer motor 120. As a result, the document is fed to the transport roller 121 by the pickup roller 123 and transported to the document reading position 152 by the transport roller.

  In step S104, the leading edge of the document is detected. When the feeding of the document is started, the leading edge detection operation of the document by the reflected light detector 142 is started. The transport operation at a constant speed continues until the leading edge of the document reaches the detection position of the reflected light detector 142. When the leading end of the conveyed document reaches the detection position of the reflected light detector 142, the reflected light detector 142 receives the reflected light. When there is a change from a state where there is no document to a state where it is present, it is determined that the leading edge has been detected.

  In step S105, image reading is started. When the leading edge of the document is detected, the document is conveyed at a specified speed according to the reading accuracy, and the image reading unit 130 reads the image. When the reflected light detector 142 receives the reflected light of the original, the trailing edge detection operation is started.

  In step S106, the trailing edge of the document is detected. During the image reading in FIG. 4D, the conveyed document passes through the detection position of the reflected light detector 142. Until the trailing edge is detected, the transport operation at the specified speed according to the reading accuracy is continued. As shown in FIG. 4E, when the rear end of the conveyed document passes the detection position of the reflected light detector 142, the reflected light detector 142 stops receiving the reflected light. When the state changes from the state where the document exists to the state where the document does not exist, it is determined that the trailing edge of the document has been detected.

  In step S107, document detection is performed. When the document is discharged to the discharge tray 153, the presence or absence of the document is checked. If there is a document on the paper feed tray 150, the process returns to step S103 to read the image of the next document. If no document is detected on the paper feed tray 150 even after a certain period of time, the process proceeds to S108.

  In step S108, the sheet feeding ends. Since there is no original, the rotation of the transport motor 120 is stopped. Further, the detection of the original by the transmitted light detector 141 and the reflected light detector 141 and the light emission of the light emitting unit 140 are terminated.

  The process ends in S109. A series of operations of image reading by automatic paper feeding is completed.

  In this manner, the number of components such as a light source for detecting a document and a drive circuit of the light source can be reduced, and power consumption can be reduced.

(Second embodiment)
The second embodiment is a control for reducing the power used by the light emitting unit when detecting a document. The system configuration and the automatic paper feed image reading mechanism use the configurations shown in FIGS.

(Light intensity adjustment)
Here, the light amount of the light emitting unit 140 when the document on the paper feed tray 150 and the document on the conveyance path are detected is set. This setting is performed when performing the initial setting, but may be performed for maintenance such as when the document cannot be detected correctly. FIG. 5 shows a flowchart for adjusting the light amount of the light emitting unit with respect to the photodetector.

  In step S501, light amount adjustment is started. The user gives an instruction to start the light quantity adjustment from the operation unit 116 or the information device 2 in the maintenance mode. Thereby, the sensor control unit 113 supplies the light emitting unit 140 with the maximum current. The range that can be supplied is, for example, a range of 5 to 10 mA as a current amount. In the case of a light source that periodically emits light, the method of changing the light amount may be to change the duty ratio. For example, when the duty ratio is 100%, the maximum light amount is obtained, and when the duty ratio is 50%, the light amount becomes half.

  In step S502, transmitted light is detected. It is determined whether the transmitted light from the light emitting unit 140 can be detected by the transmitted light detector 141. If it is determined that light can be detected by the transmitted light detector 141, the process proceeds to S503. If it is determined that the transmitted light detector 141 cannot detect light, the process proceeds to S504.

  In step S503, the light amount of the light emitting unit 140 is adjusted. The amount of current supplied to the light emitting unit 140 is set low to reduce the amount of light. If the maximum current amount cannot be detected, an error is displayed on the operation unit 116 or the information device 2 to notify the user.

  In step S504, the current amount is stored. The amount of current of the light emitting unit 140 when it is determined that the transmitted light has been detected is stored in the auxiliary storage unit 115. The current amount at this time is a set value at the time of detecting a document in the paper feed tray 150.

  In step S505, a reference sheet setting instruction is issued. Since transmitted light is detected, reflected light is detected. At this time, a reference sheet for adjusting reflected light is used to set an appropriate amount of current. Therefore, the user is instructed to set the reference sheet on the operation unit 116 or the screen of the information processing device 2.

  In step S506, reference paper is fed. The user places the reference paper on the paper feed tray 150. If it is determined that the reference paper is placed, the reference paper is fed by the transport motor 120. The reference paper is transported by the transport rollers 121 beyond the document detection position. In addition, the maximum amount of current that can be supplied to the light emitting unit 140 is supplied.

  In step S507, the reflected light is detected. It is determined whether the reflected light detector 142 can receive the reflected light from the reference paper. If it is determined that the reflected light cannot be detected, the process proceeds to S509. If it is determined that the reflected light can be detected, the process proceeds to S508.

  In step S508, the light amount of the light emitting unit 140 is adjusted. The amount of current supplied to the light emitting unit 140 is set small. If the maximum current amount cannot be detected, an error is displayed on the operation unit 116 or the information device 2 to notify the user.

  In step S509, the current amount is stored. The amount of current of the light emitting unit 140 when it is determined that the reflected light has been detected is stored in the auxiliary storage unit 115. The amount of current at this time is a set value for detecting a document at a detection position in the transport path 151.

  The process ends at S510. The supply of power to the light emitting unit 140, the transmitted light detector 141, and the reflected light detector 142 is stopped.

(Control for power saving)
FIG. 6 is a flowchart showing an operation of image reading by automatic sheet feeding for reducing power consumption of the light emitting unit.

  In step S601, image reading by automatic paper feeding is started. The user places a document on the paper feed tray 150. After that, the operation instruction of the image reading by the automatic feeding of the original is performed by using the operation unit 116 or the information device 2.

  In step S602, a current setting for detecting a document on the tray is performed. The sensor control unit 113 supplies the current amount stored in S504 to the light emitting unit 140. The sensing operation of the transmitted light detector 141 is controlled, and the original detection operation is started.

  In step S603, the presence or absence of a document on the paper feed tray 150 is detected. If the transmitted light detector 141 does not receive light, it is determined that a document exists. If a document is detected, the process advances to step S604.

  In step S604, current setting for detecting the leading edge of the document is performed. The sensor control unit 113 supplies the light amount stored in S509 to the light emitting unit 140. Further, the original detection operation of the transmitted light detector 141 is stopped, and the leading end detection operation of the reflected light detector 142 is started.

  In step S605, the document is fed. The document is fed and transported by the transport motor 120.

  In step S606, the leading edge of the document is detected. The leading end of the conveyed document reaches the detection position in the conveyance path 151, and the reflected light detector 142 receives the reflected light. When there is a change from a state where there is no document to a state where it is present, it is determined that the leading edge has been detected.

  In step S607, the image reading unit 130 performs an image reading operation. When the leading edge of the document is detected, the conveyance operation is performed at a designated speed according to the reading accuracy, and the image reading unit 130 reads the image.

  In step S608, the trailing edge of the document is detected. When the rear end of the conveyed document passes the detection position of the reflected light detector 142, the reflected light detector 142 stops receiving the reflected light. When the state changes from the state where the document exists to the state where the document does not exist, it is determined that the trailing edge of the document has been detected.

  In step S609, the detection setting of the document on the paper feed tray 150 is performed. When the document is discharged to the discharge tray 153, the presence or absence of the document is checked. The sensor control unit 113 supplies the light amount stored in S509 to the light emitting unit 140.

  In step S610, a document is detected. If the transmitted light detector 141 is blocked by the document and does not receive light, it is determined that the document exists. If there is a document in the paper feed tray 150, the process returns to S604. If there is no document on the paper feed tray 150 even after a certain period of time, the process proceeds to S611.

  In step S611, the sheet feeding ends. Since there is no original, the rotation of the transport motor 120 is stopped. Further, the detection of the original by the transmitted light detector 141 and the reflected light detector 141 and the light emission of the light emitting unit 140 are terminated.

  In S612, the process ends. The image reading by the automatic paper feeding ends.

  By doing so, it is possible to reduce the power consumption by optimizing the amount of power used by the light emitting unit when detecting a document on the sheet feed tray and the transport path.

Reference Signs List 120 transport motor 121 transport roller 130 image reading unit 140 light emitting unit 145 condenser lens 150 paper feed tray 141 transmitted light detector 142 reflected light detector

Claims (9)

An image reading unit for reading a document;
A loading section on which a plurality of originals can be placed;
A transport unit that transports a document from the placement unit to the image reading unit,
A first photodetector that detects a document placed on the placement unit by light,
A second photodetector that detects, by light, a document conveyed to the image reading unit by the conveyance unit,
A light-emitting unit commonly used by the first light detector and the second light detector,
An image reading apparatus, wherein the first photodetector and the second photodetector can receive either transmitted light from the light emitting unit or reflected light reflected by a document.   The image reading apparatus according to claim 1, wherein the first light detector and the second light detector can receive the transmitted light.   The image reading device according to claim 1, wherein the first photodetector and the second photodetector can receive the reflected light.   The image reading apparatus according to claim 1, wherein the first photodetector can receive the transmitted light, and the second photodetector can receive the reflected light.   5. The light amount is changed by changing a current amount or a light emission duty ratio of the light emitting unit after the first photodetector detects a document. 6. Image reading device.   When the state changes from a state in which the document is detected by the second photodetector to a state in which the document is not detected, and if the document is not detected by the first photodetector, the conveyance of the document by the conveyance unit is stopped. The image reading apparatus according to any one of claims 1 to 5, wherein the image reading apparatus is configured to:   The image reading apparatus according to claim 1, further comprising a document width detecting unit configured to detect a width of the document by light, wherein the light emitting unit is used as a light source of the document width detecting unit. . An image reading unit for reading a document;
A loading section on which a plurality of originals can be placed;
A transport unit for feeding a document from the placement unit to the image reading unit,
A first light detector for detecting a document in the placement unit by light,
A second photodetector that detects, by light, a document conveyed to the image reading unit by the conveyance unit, and an image reading method for an image reading apparatus, comprising:
The image reading unit has a light emitting unit commonly used by the first photodetector and the second photodetector,
A first step of detecting a document with the first photodetector;
A second step of changing a control method of the light emitting unit;
A third step of detecting a document by the second photodetector. 9. The image reading method according to claim 8, wherein the control method changes a light amount by changing a current amount or a light emission duty ratio of the light emitting unit.

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