JP2022098675A - Medium conveyance device and medium detection method - Google Patents

Abstract

To simplify the structure for detecting presence/absence of a medium, which is conventionally complicated.SOLUTION: A medium conveyance device includes: a medium placement part in which a medium is placed; a roller for conveying the medium placed in the medium placement part ina conveyance direction; an electrode arranged so as to come into contact with the medium placed in the medium placement part, and having electric conductivity; a charge detection circuit for outputting a signal with magnitude according to a movement amount of an electric charge from the medium which has come into contact with the electrode to the electrode; and a control part. The control part determines whether or not the signal outputted by the charge detection circuit is equal to or greater than a predetermined threshold value, before causing the roller to start conveyance, and when the signal outputted by the charge detection circuit is equal to or greater than the threshold value, it determines that there is a medium in the medium placement part, and when the signal outputted by the charge detection circuit is below the threshold value, it determines that there is no medium in the medium placement part.SELECTED DRAWING: Figure 5

Description

The present invention relates to a medium transfer device and a medium detection method.

Described is an image reading device that reads an image of a medium by a reading unit and generates image data based on the image while transporting the medium along a transport path (see Patent Document 1). In such an image reading device, an optical sensor for detecting a medium is provided upstream of the reading unit in the transport path.

Japanese Unexamined Patent Publication No. 2017-188542

The optical sensor includes a light emitting unit and a light receiving unit that receives light output from the light emitting unit. When the medium is in the position of the optical sensor, the light from the light emitting unit is blocked by the medium. Alternatively, in the state where the medium is present, a predetermined member has a mechanism of blocking the light from the light emitting portion. As a result, the amount of light received by the light receiving unit decreases. The medium is detected by utilizing such a change in the amount of light received by the light receiving unit. However, if an optical sensor including a light emitting unit and a light receiving unit and the member are provided in the transport path, the device configuration becomes complicated.

The medium transfer device includes a medium mounting section on which a medium is placed, a roller that transports the medium mounted on the medium mounting section in a transport direction, and the medium mounted on the medium loading section. An electrode arranged so as to be in contact with the electrode, a charge detection circuit that outputs a signal having a size corresponding to the amount of charge transfer from the medium in contact with the electrode to the electrode, a control unit, and a control unit. The control unit determines whether or not the signal output by the charge detection circuit is equal to or higher than a predetermined threshold value before starting the transfer to the roller, and the control unit determines whether or not the signal is output by the charge detection circuit. If is equal to or higher than the threshold value, it is determined that the medium is present in the medium mounting portion, and if the signal output by the charge detection circuit is less than the threshold value, it is determined that there is no medium in the medium mounting portion. do.

The medium transport device includes a medium mounting section on which the medium is placed, a roller that transports the medium mounted on the medium mounting section in the transport direction, and the medium mounted on the medium loading section. An electrode arranged so as to be in contact with the electrode, a charge detection circuit that outputs a signal having a size corresponding to the amount of charge transfer from the medium in contact with the electrode to the electrode, a control unit, and a control unit. The control unit monitors a change in a signal output by the charge detection circuit during the period from when the power of the medium transfer device is turned on until the instruction of the transfer is received, and the charge detection circuit outputs the signal. The second threshold is the difference between the signal output by the charge detection circuit after the change of the first threshold value or more occurs and the change of the first threshold value or more occurs and before the change occurs. When it is determined that the medium is present in the medium mounting portion when the value is equal to or higher than the value, and when it is determined that the medium is present in the medium mounting portion, the transfer by the roller is started according to the instruction of the transfer.

A medium detection method executed by a medium transport device including a medium mounting section on which a medium is mounted and a roller for transporting the medium mounted on the medium mounting section in a transport direction. In the transport device, a conductive electrode is arranged so as to come into contact with the medium mounted on the medium mounting portion, and the amount of charge transfer from the medium in contact with the electrode to the electrode. It is determined whether or not the signal output by the charge detection step is equal to or higher than a predetermined threshold value in the charge detection step of outputting a signal having a magnitude corresponding to the above and before the roller is started to carry the signal. If the signal output by the charge detection step is equal to or higher than the threshold value, it is determined that the medium is present in the medium mounting portion, and if the signal output by the charge detection step is less than the threshold value, the medium is determined to be present. A medium detection step for determining that there is no medium in the medium mounting portion is provided.

A side view schematically showing an image reader. The figure which shows an example of a sensor. The figure which shows the other example of a sensor. The figure which mainly shows the charge detection circuit of a sensor. The flowchart which shows the medium detection method which concerns on 1st Embodiment. The flowchart which shows the medium detection method which concerns on 2nd Embodiment. The flowchart which shows the medium detection method which concerns on 3rd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to each figure. It should be noted that each figure is merely an example for explaining the present embodiment. Since each figure is an example, the ratio and shape may not be accurate, may not be consistent with each other, or may be partially omitted.

1. 1. Device configuration:
FIG. 1 schematically shows the image reading device 10 according to the present embodiment by a side view. The image reading device 10 includes a medium transporting device 20. The image reading device 10 itself may be referred to as a medium transporting device. The media carrier implements the media detection method. The image reading device 10 brings the housing 10A, the medium mounting section 11 on which one or more media M are stacked, and the medium M mounted on the medium mounting section 11 into the transport path 100. A medium transport device 20 for transporting along the line is provided. The medium transfer device 20 is provided in the housing 10A. The medium M is a document to be read, and is, for example, an insulating material such as paper. The medium mounting unit 11 may be referred to as a document tray or a paper feed tray.

The image reading device 10 includes a reading unit that reads an image of the medium M conveyed along the conveying path 100. In the example of FIG. 1, the image reading device 10 includes, as a reading unit, a first reading unit 12 for reading an image on the front surface of the medium M and a second reading unit 13 for reading an image on the back surface of the medium M.

The medium transport device 20 includes a feed roller 21 that transports the medium M mounted on the medium mounting section 11 toward the reading sections 12 and 13, and a nip section 2 2 that nip the medium M together with the feed roller 21. To prepare for. The feed roller 21 corresponds to a roller that conveys the medium M mounted on the medium mounting portion 11 in the transport direction X. Transporting in the transporting direction X means transporting from upstream to downstream in the transporting direction X. The upstream and downstream of the transport direction X or the upstream and downstream of the transport path 100 are simply referred to as upstream and downstream. For each roller such as the feed roller 21, the rotation in the direction of sending the medium M to the downstream is called "forward rotation", and the rotation in the direction of sending the medium M to the upstream is called "reverse rotation".

Examples of the nip portion 22 include a separation roller and a separation plate. When the separation roller is adopted as the nip portion 22, the separation roller may be restricted in its rotation or may be rotated in the reverse direction. The separation plate does not rotate like the separation roller, but generates a constant frictional force and comes into contact with the medium M. The separation roller and the separation plate correspond to a "separation unit" that separates the medium M to be conveyed from the other media M laminated on the medium mounting unit 11.

In the medium transfer device 20, the medium M is niped by the feeding roller 21 and the nip portion 22. At this time, the medium M rubs against both the feeding roller 21 and the nip portion 22. Therefore, static electricity is generated between the medium M and the feeding roller 21, and static electricity is generated between the medium M and the nip portion 22. As a result, both the front surface and the back surface of the medium M are charged. Further, simply, when the medium M is placed on the medium mounting portion 11, it rubs against the feeding roller 21, the nip portion 22, and the medium mounting portion 11, and static electricity is generated, and the medium M is charged.

The medium transfer device 20 includes a transfer roller 231 and 232 arranged between the feed roller 21 and the reading units 12 and 13 in the transfer direction X, and a discharge roller 241 arranged downstream of the reading units 12 and 13. It is equipped with 242. The medium transfer device 20 includes a drive motor 25 that is a power source for the feed roller 21, the transfer roller 231 and the discharge roller 241. When the output of the drive motor 25 is transmitted to the feed roller 21, the transfer roller 231 and the discharge roller 241, the feed roller 21, the transfer rollers 231,232 and the discharge rollers 241,242 rotate, so that they are upstream along the transfer path 100. The medium M is transported from the to the downstream.

The medium transfer device 20 includes a sensor 32 that detects the medium M mounted on the medium mounting unit 11. The sensor 32 has an electrode 41 arranged so as to come into contact with the medium M mounted on the medium mounting portion 11, and a charge detection circuit 42 connected to the electrode 41. As shown in FIG. 1, the electrode 41 is provided at a position upstream of the position where the feeding roller 21 is in contact with the medium M. Further, as shown in FIG. 1, the electrode 41 is provided at a position upstream of the nip portion 22 as a separation portion.

2 and 3 briefly show an example of the sensor 32, respectively.
As the electrode 41, for example, a brush-shaped electrode can be mentioned as shown in FIG. In this case, the electrode 41 has a plurality of fibers 45 and a base 46 to which the base end of each fiber 45 is fixed. The fiber 45 is made of a conductive material. That is, the electrode 41 has conductivity. Therefore, when each fiber 45 comes into contact with the medium M, the electric charge attached to the medium M moves to the electrode 41. Then, the electric charge transferred to the electrode 41 moves toward the electric charge detection circuit 42 via the wiring 47.

Further, the electrode 41 may be, for example, a plate-shaped conductive plate 45A as shown in FIG. Even in this case, the electrode 41 has conductivity. Therefore, when the medium M comes into contact with the conductive plate 45A, the electric charge attached to the medium M moves to the conductive plate 45A. Then, the electric charge transferred to the conductive plate 45A moves toward the electric charge detection circuit 42 via the wiring 47.

The medium transfer device 20 employs a "lower pick" that sequentially conveys the media M one by one from the bottom of the bundle of the media M in a situation where a plurality of media M are stacked on the medium mounting portion 11. It may be a configuration that employs an “upper pick” that sequentially conveys the media M one by one from the top of the bundle of the media M. In the example of FIG. 1, it can be seen from the arrangement of the feeding roller 21 and the nip portion 22 with respect to the medium mounting portion 11 that the lower pick is adopted.

In the configuration in which the medium transfer device 20 employs the lower pick, as shown in FIG. 3, the electrode 41 arranged so as to be in contact with the medium M from below is a suitable example as the electrode 41 of the sensor 32. I can say. On the other hand, in the configuration in which the medium transfer device 20 employs the upper pick, as shown in FIG. 2, the electrode 41 arranged so as to be in contact with the medium M from above is suitable as the electrode 41 of the sensor 32. It can be said to be an example.

FIG. 4 shows an example of the charge detection circuit 42 of the sensor 32. According to FIG. 4, the charge detection circuit 42 is a grounded emitter circuit. The charge detection circuit 42 has a bipolar transistor 421. In FIG. 4, the arrow from the medium M to the electrode 41 indicates the transfer of charge from the medium M to the electrode 41.

The electrode 41 is connected to the base 42B of the bipolar transistor 421. The emitter 42E of the bipolar transistor 421 is grounded. A resistance 422 is connected to the collector 42C of the bipolar transistor 421 via the wiring 48. A control unit 60 is connected to the wiring 48 located between the collector 42C and the resistor 422. That is, a signal having a magnitude corresponding to the amount of electric charge transferred from the medium M to the electrode 41 is input to the base 42B of the bipolar transistor 421. Then, the collector 42C of the bipolar transistor 421 outputs an amplified signal SGa, which is a signal obtained by amplifying the signal input to the base 42B, to the control unit 60. The control unit 60 has a CPU as a processor and a memory. The control unit 60 controls the image reading device 10 including the medium transfer device 20 according to the program stored in the memory.

The image reading device 10 has a display unit 14. The display unit 14 is a means for displaying visual information, and is composed of, for example, a liquid crystal display, an organic EL display, or the like. The display unit 14 is arranged at a position easily visible to the user on the outer surface of the housing 10A, and displays an image under the control of the control unit 60. Further, although not particularly shown, the image reading device 10 has various interfaces for receiving operations and signals from the outside. Of course, the display unit 14 can also function as a touch panel capable of accepting operations from the outside.

In the present embodiment, the image reading device 10 will be described as a specific example of the medium transporting device, but the media transporting device may be, for example, a printing device. That is, a printing device that includes the characteristics of the medium transport device according to the present embodiment and executes printing on a medium such as paper transported from the medium mounting unit may be assumed.
Hereinafter, some embodiments will be described.

2. 2. First Embodiment:
FIG. 5 shows a medium detection method according to the first embodiment by a flowchart.
After the power of the image reading device 10 is turned on, the control unit 60 starts the flowchart of FIG. 5 according to the program. The control unit 60 repeatedly determines whether or not a scan instruction has been received from the user (step S100). When the control unit 60 receives the scan instruction, the control unit 60 proceeds to step S110 from the determination of "Yes" in step S100. The scan instruction is a transfer instruction of the medium M for the medium transfer device 20.

After the power of the image reading device 10 is turned on, the signal value SV, which is the magnitude of the amplified signal SGa, is continuously output from the charge detection circuit 42. That is, the charge detection circuit 42 executes a "charge detection step" that outputs a signal having a magnitude corresponding to the amount of charge transfer from the medium M in contact with the electrode 41 to the electrode 41. The control unit 60 inputs the signal value SV. In other words, after the power of the image reading device 10 is turned on, the control unit 60 monitors the change of the signal value SV output by the charge detection circuit 42. The signal value SV increases as the amount of electric charge transferred from the medium M to the electrode 41 increases.

Therefore, in step S110, the control unit 60 determines whether or not a signal value SV having a predetermined threshold value TH or higher has been input from the time when the power of the image reading device 10 is turned on to the present. A value for determining whether or not the medium M is in contact with the electrode 41 based on the magnitude of the signal value SV is preset as a threshold value TH. That is, when the signal value SV is equal to or higher than the threshold value TH, the medium M is in contact with the electrode 41. On the other hand, when the signal value SV is less than the threshold value TH, the medium M is not in contact with the electrode 41. The control unit 60 proceeds from the determination of “Yes” to step S120 when the signal value SV equal to or higher than the threshold value TH is input, and when the signal value SV equal to or higher than the threshold value TH cannot be input, the control unit 60 proceeds to “No”. From the determination of "", the process proceeds to step S140. In step S110, the control unit 60 does not simply compare the signal value SV with the threshold value TH, but when it can detect a change amount equal to or higher than the threshold value TH as the change amount of the signal value SV, " It may be determined as "Yes".

In step S120, the control unit 60 determines that the medium M is present in the medium mounting unit 11, and proceeds to step S130. In step S130, the scanning process of the medium M is started in response to the scanning instruction recognized in step S100. That is, the control unit 60 rotates the feed roller 21 by the drive motor 25 and starts the transfer of the medium M from the medium mounting unit 11. Although not particularly described in FIG. 5 after the scan process is started in step S130, the control unit 60 naturally rotates the transport roller 231 and the discharge roller 241 by the drive motor 25 to transport the medium M to the transport path 100. The first reading unit 12 and the second reading unit 13 are made to read the medium M to be conveyed.

On the other hand, in step S140, the control unit 60 determines that the medium mounting unit 11 does not have the medium M, and ends the flowchart of FIG. In this case, step S130 is not executed. That is, the transport of the medium M from the medium mounting unit 11 is not started in response to the scan instruction recognized in step S100.
As described above, the flow of the process of branching from step S110 to step S120 or step S140 corresponds to the "medium detection step".

As described in parentheses in step S120, when the control unit 60 determines that the medium mounting unit 11 has the medium M, the control unit 60 indicates that the medium mounting unit 11 has the medium M, for example, by a message or an illustration. , May be displayed on the display unit 14. Further, as described in parentheses in step S140, when the control unit 60 determines that the medium mounting unit 11 does not have the medium M, a message, an illustration, or the like indicating that the medium mounting unit 11 does not have the medium M. Therefore, it may be displayed on the display unit 14.

The control unit 60 may repeatedly execute steps S110 and subsequent steps after completing the scanning process for one medium M through step S130. As a result, in the situation where the medium M before reading remains in the medium mounting unit 11 or the user is replenishing the supply of the medium M to the medium mounting unit 11, the media M is scanned one by one in order. Processing can be performed. On the other hand, when the flowchart of FIG. 5 is completed through step S140, the control unit 60 may start the flowchart of FIG. 5 again from step S100.

3. 3. Second embodiment:
FIG. 6 shows a medium detection method according to the second embodiment by a flowchart.
Regarding the second embodiment, the description common to the first embodiment will be omitted. FIG. 6 differs in that it has step S105 when compared to FIG.

In the first embodiment, when the medium M is placed on the medium mounting unit 11 during the period from when the power of the image reading device 10 is turned on until the scan instruction is input, the medium M is placed on the medium mounting unit 11. Static electricity is generated by the rubbing between the medium M and the surroundings at that time, and it is easy to determine "with medium" by the signal value SV corresponding to the electric charge attached to the medium M. On the other hand, when the medium M is placed on the medium mounting unit 11 before the power of the image reading device 10 is turned on, a signal value SV sufficient to reach the threshold value TH is obtained even though the medium M is present. It is assumed that it will not be possible.

In view of such a situation, in the second embodiment, if the control unit 60 determines “Yes” in step S100, the process proceeds to step S105, controls the drive motor 25 to rotate the feed roller 21 in the forward direction, and , Reverse rotation. When the medium M is present in the medium mounting portion 11, the medium M is pulled downstream by the forward rotation of the feeding roller 21, and the medium M is returned upstream by the reverse rotation of the feeding roller 21. With such pulling in and returning, the feeding roller 21 and the medium M rub against each other to generate static electricity, and electric charges adhere to the medium M. That is, if the medium M is present in the medium mounting portion 11, as a result of step S105, the medium M in the medium mounting portion 11 is forcibly charged.

Since the forward rotation of the feeding roller 21 in step S105 may cause rubbing between the feeding roller 21 and the medium M to the extent that static electricity is generated, the medium M may be slightly moved downstream or almost. Alternatively, the amount of rotation is such that the medium M is not moved at all. Therefore, the forward rotation of the feed roller 21 in step S105 is not included in the concept of transporting the medium M downstream for reading. Similarly, the reverse rotation of the feeding roller 21 in step S105 may cause rubbing between the feeding roller 21 and the medium M to the extent that static electricity is generated, so that the medium M is slightly moved upstream. Or, the amount of rotation is such that the medium M is hardly or not moved at all.

It should be noted that static electricity is generated due to the rubbing between the feeding roller 21 and the medium M only by the above-mentioned pulling. Therefore, in step S105, the reverse rotation of the feed roller 21 is not essential. That is, the control unit 60 may rotate the feed roller 21 in the forward direction in step S105 and may not execute the reverse rotation thereafter. By omitting the reverse rotation in step S105, it is possible to shorten the time from the determination of “Yes” in step S110 to the start of transporting the medium M when scanning is started in step S130.

In the second embodiment, the control unit 60 performs step S110 following step S105. In this step S110, the control unit 60 may compare the signal value SV input from the charge detection circuit 42 after step S105 with the threshold value TH. As described above, if the medium M is present in the medium mounting portion 11, the electric charge adheres to the medium M in the medium mounting portion 11 in accordance with step S105, so that step S110 is determined as “Yes”. Steps S120 and S130 will be executed. On the other hand, if there is no medium M in the medium mounting unit 11, even if step S105 is executed, the signal value SV input from the charge detection circuit 42 does not change and remains low, so that step S110 is "No". The determination is made, and the process proceeds to step S140.

In the second embodiment, the control unit 60 may repeatedly execute steps S105 and subsequent steps after completing the scanning process for one medium M through step S130. On the other hand, when the flowchart of FIG. 6 is completed through step S140, the control unit 60 may start the flowchart of FIG. 6 again from step S100.

4. Third embodiment:
FIG. 7 shows the medium detection method according to the third embodiment by a flowchart.
As for the third embodiment, the description of the first embodiment and the second embodiment shall be applied mutatis mutandis. After the power of the image reading device 10 is turned on, the control unit 60 starts the flowchart of FIG. 7 according to the program. As described above, after the power of the image reading device 10 is turned on, the control unit 60 monitors the change of the signal value SV output by the charge detection circuit 42.

In step S200, the control unit 60 determines whether or not there is a change amount of the predetermined first threshold value TH1 or more as the change amount of the signal value SV. Although it has been explained that the change amount of the signal value SV and the threshold value may be compared with respect to step S110, the change amount of the signal value SV is also compared with the threshold value in step 200. The first threshold value TH1 may be the same value as the threshold value TH adopted in step S110, or may be a different value. The first threshold value TH1 is, for example, about +200 mV. When the change amount of the signal value SV is equal to or more than the first threshold value TH1, the control unit 60 proceeds to step S210 from the determination of “Yes”, and the change amount of the signal value SV is less than the first threshold value TH1. If there is, the process proceeds from the determination of “No” to step S230.

In step S210, the control unit 60 determines whether or not the difference between the signal value SV after the change of the first threshold value TH1 or more occurs and before the change occurs is the predetermined second threshold value TH2 or more. do. The control unit 60 proceeds from the determination of “Yes” to step S220 when the difference is equal to or greater than the second threshold value TH2, and “No” when the difference is less than the second threshold value TH2. From the determination, the process proceeds to step S230.

In FIG. 7, in the vicinity of steps S200 and S210, the state of change in the signal value SV with the passage of time is illustrated in parentheses. For example, when the medium M is placed on the medium mounting portion 11, the medium M and the surroundings rub against each other, the medium M is charged with static electricity, and the change amount dv1 is generated in the signal value SV output by the charge detection circuit 42. .. In step S200, it is assumed that such a change amount dv1 becomes the first threshold value TH1 or more, and the determination of “Yes” proceeds to step S210.

The "signal value SV after a change of the first threshold value TH1 or more occurs" is not a value at the time when a change of the first threshold value TH1 or more occurs, but is, for example, a signal value after a predetermined time has elapsed. Refers to a value in which the SV level is stable to some extent. According to FIG. 7, the difference between the value when the signal value SV is slightly settled after the change amount dv1 of the first threshold value TH1 or more is generated and the signal value SV before the change amount dv1 is generated. A certain amount of change dv2 is "the difference in signal value SV between after a change of the first threshold value TH1 or more occurs and before it occurs". In step S210, if such a change amount dv2 is equal to or greater than the second threshold value TH2, the determination of “Yes” proceeds to step S220. It may be understood that TH1> TH2.

Not only when the medium M is placed on the medium mounting portion 11, but also when the medium M placed on the medium mounting portion 11 is removed, static electricity is generated due to the rubbing between the medium M and the medium mounting portion 11 and the like. As a result of the generation and the electrode 41 picking up static electricity, it may be determined as "Yes" in step S200. That is, even if it is determined as "Yes" by step S200, it cannot be said that the medium M is surely present in the medium mounting portion 11. On the other hand, since a certain amount of electric charge is attached to the medium M, a comparison between the situation where the medium M is present in the medium mounting portion 11 and the situation where the medium M is not present in the medium mounting portion 11 is compared. The signal value SV is higher in the situation where the medium M is present in the unit 11. Therefore, in the third embodiment, the determination in step S210 is performed, and the "difference in signal value SV between after the change of the first threshold value TH1 or more occurs and before the change occurs" is a positive value of a certain degree or more. If there is, it can be said that the medium M is placed in the medium mounting unit 11, so it is determined as “Yes”. On the contrary, if the "difference in signal value SV between after the change of the first threshold value TH1 or more occurs and before it occurs" is small or a negative value, the medium M from the medium mounting unit 11 Is highly likely to have been removed, so it is determined as "No" in step S210.

In step S220, the control unit 60 determines whether or not a scan instruction has been received from the user, as in step S100. When the control unit 60 receives the scan instruction, the control unit 60 proceeds to step S270 from the determination of "Yes". If the control unit 60 does not recognize that the scan instruction has been received, the control unit 60 returns to step S200 from the determination of "No".
Step S270 and subsequent steps S280 are the same as the flow of steps S120 and S130.

In step S230, the control unit 60 determines whether or not a scan instruction has been received from the user, as in step S220. When the control unit 60 receives the scan instruction, the control unit 60 proceeds to step S240 from the determination of "Yes". If the control unit 60 does not recognize that the scan instruction has been received, the control unit 60 returns to step S200 from the determination of "No".
That is, the control unit 60 steps while monitoring the change in the signal value SV output by the charge detection circuit 42 during the period from when the power of the medium transfer device is turned on to when the transfer instruction (= scan instruction) is received. The determination of S200 and step S210 is performed.

In step S240, the control unit 60 determines whether or not a signal value SV having or equal to a predetermined third threshold value TH3 has been input from the time when the power of the image reading device 10 is turned on to the present. When the control unit 60 inputs a signal value SV having a third threshold value TH3 or higher, the control unit 60 proceeds from the determination of “Yes” to step S270, and cannot input a signal value SV having a third threshold value TH3 or higher. Then, from the determination of "No", the process proceeds to step S250. In step S240, the signal value SV may be simply compared with the third threshold value TH3, not the amount of change in the signal value SV as described in steps S110, S200, and S210.

Step S240 is a determination mainly for dealing with a situation in which the medium M is placed on the medium mounting unit 11 before the power of the image reading device 10 is turned on. When the medium M is placed on the medium mounting unit 11 before the power is turned on, the signal value SV hardly changes after the power is turned on, so there is a high possibility that the result is determined as "No" in step S200. However, as described above, when the medium mounting unit 11 has the medium M, a higher signal value SV may be obtained as compared with the case where the medium mounting unit 11 does not have the medium M. In particular, when a bundle of a plurality of media M is placed on the medium mounting portion 11, a higher signal value SV can be easily obtained as compared with the case where the medium mounting portion 11 does not have the medium M. Therefore, a third threshold is used as an appropriate threshold value for distinguishing the signal value SV obtained when the medium mounting unit 11 has the medium M from the signal value SV when the medium mounting unit 11 does not have the medium M. The value TH3 is set.

The flow of step S250, subsequent steps S260, and proceeding from “Yes” in step S260 to step S270 is the same as the flow of “Yes” and S120 in steps S105 and S110 of the second embodiment. The flow from "No" in step S260 to step S290 is the same as the flow in "No" and S140 in step S110. In step S260, the control unit 60 may compare the signal value SV input from the charge detection circuit 42 after step S250 with the predetermined fourth threshold value TH4.

That is, in the third embodiment, when it is not possible to determine “Yes” in step S240, the medium M in the medium mounting unit 11 is forcibly charged in step S250, and the medium mounting unit 11 is tentatively charged. If there is a medium M in, it is possible to determine "there is a medium". In step S260, the signal value SV to be compared with the fourth threshold value TH4 may be a change amount of the signal value SV as in step S110 of the second embodiment. The fourth threshold value TH4 may be the same value as the first threshold value TH1 adopted in step S200, or may be a different value. In the third embodiment, when the control unit 60 finishes the scanning process for one medium M through step S280 or finishes the flowchart of FIG. 7 through step S290, the flowchart of FIG. 7 is displayed again. Just start.

5. summary:
As described above, according to the present embodiment, the medium transport device is a roller (supply) that transports the medium mounting section 11 on which the medium is mounted and the medium M mounted on the medium mounting section 11 in the transport direction X. The feed roller 21), the electrode 41 arranged so as to be in contact with the medium M mounted on the medium mounting portion 11, and the conductive electrode 41, and the amount of charge transfer from the medium M in contact with the electrode 41 to the electrode 41. A charge detection circuit 42 that outputs a signal having a magnitude corresponding to the above and a control unit 60 are provided.

Then, the control unit 60 determines whether or not the signal output by the charge detection circuit 42 is equal to or higher than a predetermined threshold value before starting the transfer to the roller, and the signal output by the charge detection circuit 42 is output. If it is equal to or higher than the threshold value, it is determined that the medium mounting unit 11 has the medium M, and if the signal output by the charge detection circuit 42 is less than the threshold value, it is determined that the medium mounting unit 11 does not have the medium M. ..
According to the above configuration, the medium is placed without complicating the device configuration by providing each member such as an optical sensor having a light emitting unit and a light receiving unit and a member that moves so as to block the light from the light emitting unit as in the conventional case. Before starting the transfer of the medium M from the unit 11, it can be determined whether or not the medium M is present in the medium mounting unit 11.

Further, according to the present embodiment, the electrode 41 is provided at a position upstream of the position where the roller is in contact with the medium M in the transport direction X.
Further, according to the present embodiment, the medium transfer device includes a separation unit that separates the medium M to be transferred from the other medium M laminated on the medium mounting unit 11, and the electrode 41 has a transfer direction X. In, it may be provided at a position upstream from the separation portion.
According to these configurations, the position of the electrode 41 suitable for determining whether or not the medium M is present in the medium mounting portion 11 is specified before starting the transfer of the medium M from the medium mounting portion 11. Present.
However, a part of the electrode 41 may be provided at a position downstream of the position where the roller is in contact with the medium M, or at a position downstream of the separation portion.

Further, according to the present embodiment, the medium transfer device includes a display unit 14. Then, when the control unit 60 determines that the medium mounting unit 11 has the medium M, the control unit 60 causes the display unit 14 to indicate that the medium mounting unit 11 has the medium M, and the medium mounting unit 11 does not have the medium M. If it is determined, the display unit 14 may display that the medium mounting unit 11 does not have the medium M.
According to the above configuration, the user can be notified of the determination result of the presence or absence of the medium. Further, it is possible to notify the user that the medium M is not present in the medium mounting unit 11 and prompt the user to place the medium M in the medium mounting unit 11.

Further, according to the present embodiment, when the control unit 60 determines that the medium mounting unit 11 has the medium M, the control unit 60 starts the transfer by the roller, and when it determines that the medium mounting unit 11 does not have the medium M, the control unit 60 starts the transfer. The transfer by the roller is not started.
According to the above configuration, when the medium mounting unit 11 does not have the medium M, it is possible to avoid unnecessary movement such as driving a roller for transportation from the medium mounting unit 11.

Further, according to the present embodiment, the control unit 60 causes the roller to perform forward rotation, which is the rotation of the roller in the direction of sending the medium M in the transport direction X, before the roller is started to carry. In the above, it may be determined whether or not the signal output by the charge detection circuit 42 is equal to or greater than the threshold value.
According to the above configuration, by performing a process of forcibly charging the medium M before starting the transfer of the medium M from the medium mounting unit 11, the accuracy of determining the presence or absence of the medium M in the medium mounting unit 11 is performed. Can be further enhanced.
The control unit 60 causes the roller to perform forward rotation before causing the roller to start the transfer, and further performs reverse rotation, which is the rotation of the roller in the direction of feeding the medium M in the direction opposite to the transfer direction X. After the roller is made to execute, it may be determined whether or not the signal output by the charge detection circuit 42 is equal to or greater than the threshold value.

Further, according to the present embodiment, the control unit 60 monitors a change in the signal output by the charge detection circuit 42 during the period from when the power of the medium transfer device is turned on to when the transfer instruction is received, and the charge detection circuit. The difference between the signal output by the charge detection circuit 42 after the change of the first threshold value TH1 or more occurs in the signal output by 42 and before and after the change of the first threshold value TH1 or more occurs. When is determined to have the medium M in the medium mounting unit 11 and it is determined that the medium M is present in the medium mounting unit 11 when is equal to or higher than the second threshold value TH2, the above-mentioned The transfer by the roller (feeding roller 21) may be started.
According to the above configuration, it is possible to determine “with medium” with high accuracy in the case where the medium M is placed on the medium mounting unit 11 after the power is turned on.

Further, according to the present embodiment, the control unit 60 does not generate a change of the first threshold value TH1 or more in the signal output by the charge detection circuit 42, or a change of the first threshold value TH1 or more occurs. If the difference between the signal output by the charge detection circuit 42 and the signal output by the charge detection circuit 42 is less than the second threshold value TH2, is the signal output by the charge detection circuit 42 greater than or equal to the third threshold value TH3? If it is determined whether or not the signal is output by the charge detection circuit 42 of the third threshold value TH3 or more, it may be determined that the medium M is present in the medium mounting unit 11.
According to the above configuration, it is easy to determine "with medium" in the case where the medium M is placed on the medium mounting portion 11 before the power is turned on.

Further, according to the present embodiment, the control unit 60 rotates the roller in the direction of sending the medium M in the transport direction X when the signal output by the charge detection circuit 42 is less than the third threshold value TH3. After causing the roller to perform forward rotation, it is determined whether or not the signal output by the charge detection circuit 42 is equal to or higher than the fourth threshold value TH4, and the signal output by the charge detection circuit 42 is the fourth. If the threshold value is TH4 or more, it is determined that the medium M is present in the medium mounting unit 11, and if the signal output by the charge detection circuit 42 is less than the fourth threshold value TH4, the medium is placed in the medium mounting unit 11. It may be determined that there is no M.
According to the above configuration, the medium M is forcibly forced in the case where the presence or absence of the medium M in the medium mounting portion 11 is not determined even by the determination using the first, second, and third threshold values TH1, TH2, and TH3. By performing the charging process, the presence / absence of the medium M can be determined with high accuracy.

The present embodiment discloses not only an apparatus but also inventions of each category such as a medium detection method and a program for causing a processor to execute the medium detection method.
For example, a medium transport device including a medium mounting section 11 on which the medium M is mounted and a roller (feeding roller 21) for transporting the medium M mounted on the medium mounting section 11 in the transport direction X. In the medium detecting method to be executed, the conductive electrode 41 is arranged in the medium transport device so as to be in contact with the medium M mounted on the medium mounting portion 11, and is in contact with the electrode 41. A predetermined threshold value is a signal output by the charge detection step, which outputs a signal having a size corresponding to the amount of movement of the charge from the medium M to the electrode 41, and before starting the transfer to the roller. It is determined whether or not the above is the case, and if the signal output by the charge detection step is equal to or greater than the threshold value, it is determined that the medium M is present in the medium mounting unit 11, and the signal output by the charge detection step is output. If it is less than the threshold value, a medium detection step of determining that the medium mounting unit 11 does not have the medium M is provided.
Of course, the invention of the method corresponding to the second embodiment and the third embodiment can also be grasped.

10 ... Image reading device, 10A ... Housing, 11 ... Media mounting unit, 12 ... First reading unit, 13 ... Second reading unit, 14 ... Display unit, 20 ... Media transfer device, 21 ... Feeding roller, 22 ... Nip part, 25 ... Drive motor, 32 ... Sensor, 41 ... Electrode, 42 ... Charge detection circuit, 42B ... Base, 42C ... Collector, 42E ... Emitter, 45 ... Fiber, 45A ... Conductive plate, 46 ... Base, 47 ... wiring, 48 ... wiring, 60 ... control unit, 100 ... transfer path, 231 ... transfer roller, 232 ... transfer roller, 241 ... discharge roller, 242 ... discharge roller, 421 ... bipolar transistor, 422 ... resistance, M ... medium.

Claims (11)

The medium placement part on which the medium is placed and the medium placement section
A roller that conveys the medium mounted on the medium mounting portion in the transport direction,
An electrode arranged so as to be in contact with the medium placed on the medium mounting portion and having conductivity,
A charge detection circuit that outputs a signal having a magnitude corresponding to the amount of charge transfer from the medium in contact with the electrode to the electrode.
With a control unit,
The control unit
Before starting the transfer to the roller, it is determined whether or not the signal output by the charge detection circuit is equal to or higher than a predetermined threshold value.
If the signal output by the charge detection circuit is equal to or higher than the threshold value, it is determined that the medium is present in the medium mounting portion.
A medium transfer device, characterized in that if the signal output by the charge detection circuit is less than the threshold value, it is determined that there is no medium in the medium mounting portion. The medium transfer device according to claim 1, wherein the electrode is provided at a position upstream of the position where the roller comes into contact with the medium in the transfer direction. A separation portion for separating the medium to be conveyed from the other media laminated on the medium mounting portion is provided.
The medium transfer device according to claim 2, wherein the electrode is provided at a position upstream of the separation portion in the transfer direction. Equipped with a display
The control unit
When it is determined that the medium is present in the medium mounting portion, the display unit is displayed to indicate that the medium is present in the medium mounting portion.
6. Media transfer device. The control unit
When it is determined that the medium is present in the medium mounting portion, the transfer by the roller is started.
The medium transfer device according to any one of claims 1 to 4, wherein if it is determined that the medium is not present in the medium mounting portion, the transfer by the roller is not started. The control unit causes the rollers to perform forward rotation, which is the rotation of the rollers in the direction of feeding the medium in the transport direction, before the rollers start the transfer, and then the charge detection circuit outputs the output. The medium transfer device according to any one of claims 1 to 5, wherein it is determined whether or not the signal to be generated is equal to or higher than the threshold value. The control unit causes the roller to perform the forward rotation before the roller starts the transfer, and further performs the reverse rotation, which is the rotation of the roller in the direction of feeding the medium in the direction opposite to the transfer direction. The medium transfer device according to claim 6, wherein the medium transfer device is executed by a roller and then determines whether or not the signal output by the charge detection circuit is equal to or higher than the threshold value. It is a medium transfer device
The medium placement part on which the medium is placed and the medium placement section
A roller that conveys the medium mounted on the medium mounting portion in the transport direction,
An electrode arranged so as to be in contact with the medium placed on the medium mounting portion and having conductivity,
A charge detection circuit that outputs a signal having a magnitude corresponding to the amount of charge transfer from the medium in contact with the electrode to the electrode.
With a control unit,
The control unit
During the period from when the power of the medium transfer device is turned on to when the transfer instruction is received, the change in the signal output by the charge detection circuit is monitored.
A signal output by the charge detection circuit after a change of the first threshold value or more occurs in the signal output by the charge detection circuit and after and before the change of the first threshold value or more occurs. When the difference between the two is equal to or greater than the second threshold value, it is determined that the medium is present in the medium mounting portion.
A medium transfer device, characterized in that, when it is determined that a medium is present in the medium mounting portion, transfer by the roller is started in response to the transfer instruction. The control unit
The signal output by the charge detection circuit does not have a change of the first threshold value or more, or the charge detection circuit outputs after and before the change of the first threshold value or more occurs. When the difference between the signals to be output is less than the second threshold value, it is determined whether or not the signal output by the charge detection circuit is equal to or greater than the third threshold value.
The medium transfer device according to claim 8, wherein if the signal output by the charge detection circuit is equal to or higher than the third threshold value, it is determined that the medium is present in the medium mounting portion. The control unit
When the signal output by the charge detection circuit is less than the third threshold value, the roller is made to perform normal rotation, which is the rotation of the roller in the direction of sending the medium in the transport direction. It is determined whether or not the signal output by the charge detection circuit is equal to or higher than the fourth threshold value.
If the signal output by the charge detection circuit is equal to or higher than the fourth threshold value, it is determined that there is a medium in the medium mounting portion.
The medium transfer device according to claim 9, wherein if the signal output by the charge detection circuit is less than the fourth threshold value, it is determined that there is no medium in the medium mounting portion. A medium detection method executed by a medium transport device including a medium mounting section on which a medium is mounted and a roller for transporting the medium mounted on the medium mounting section in a transport direction.
In the medium transfer device, a conductive electrode is arranged so as to come into contact with the medium mounted on the medium mounting portion.
A charge detection step of outputting a signal having a magnitude corresponding to the amount of charge transfer from the medium in contact with the electrode to the electrode.
Before starting the transfer to the roller, it is determined whether or not the signal output by the charge detection step is equal to or higher than a predetermined threshold value, and the signal output by the charge detection step is equal to or higher than the threshold value. If this is the case, it is determined that the medium is present in the medium mounting portion, and if the signal output by the charge detection step is less than the threshold value, it is determined that there is no medium in the medium mounting portion. , A medium detection method comprising.

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