JP2019070613A - Recording medium conveying apparatus and image recording apparatus - Google Patents

Abstract

To detect an arrival of a recording medium having a different shape without increasing the number of optical sensors, thereby reducing cost.SOLUTION: An image recording apparatus 1 comprises: an optical sensor 110 that includes a plurality of light emitting devices 101 and a plurality of light emitting devices 102 in which the optical axes of the plurality of light emitting devices 101 and the optical axes of the plurality of light emitting devices 102 are provided alternately in a line shape, in a width direction intersecting with a conveyance direction of a recording medium 103 conveyed by a conveyance roller 108; and a main control substrate 109 that detects an arrival of the recording medium 103 conveyed by the conveyance roller 108 to the light emitting devices 102 on the basis of quantity of light received by the plurality of light emitting devices 102.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a recording medium transport apparatus and an image recording apparatus capable of transporting recording media of various shapes.

  An image recording apparatus for recording an image on a recording medium conveyed by a recording medium conveyance apparatus equipped with an optical sensor generally uses an optical tip of the recording medium as a judgment reference for starting recording on the recording medium. It detects with the sensor. Further, in the image recording apparatus, in order to detect the movement distance of the recording medium, position detection means such as an encoder arranged to follow the recording medium or the conveyance roller is provided. Then, the image recording apparatus is a recording medium based on position information when the front end of the recording medium is detected by the optical sensor, and a movement distance from the position at which the front end detected by the position detection unit is detected to the recording start position. Determine the timing of recording start for.

  The leading end of an A4 or A3 size recording medium defined in the JIS standard, or the leading end of a recording medium such as a label or a card having four sides orthogonal to each other is orthogonal to the conveyance direction of the recording medium. It is sufficient if at least one optical sensor for detecting the leading end of the recording medium having the leading end orthogonal to the conveyance direction is disposed in the width direction orthogonal to the conveyance direction of the recording medium. It is.

  On the other hand, in recent years, not only recording media in which four sides are orthogonal to each other, recording media of various shapes such as round, elliptical, trapezoidal, parallelogram, triangle or star exist. The timing at which the optical sensor detects the leading end of the recording medium having a shape in which the four sides are not orthogonal to one another varies depending on the arrangement position of the optical sensor in the width direction orthogonal to the conveyance direction of the recording medium.

  On the other hand, conventionally, position discrimination means such as marks are provided in advance at the tip of the recording medium, and the position discrimination means is detected by an optical sensor to accurately detect the tip of the recording medium of any shape. It is possible to start recording on the recording medium at a proper timing. In the related art, a movable optical sensor is provided, and the optical sensor is moved to an appropriate position for each recording medium based on the determination of the user to detect the leading end of the recording medium. Furthermore, conventionally, there is known one in which a plurality of optical sensors are arranged in parallel in the width direction, an optical sensor corresponding to the shape of the recording medium is manually or automatically selected, and the leading end of the recording medium is detected.

  However, in the case where the position determination means (marks on the tip, etc.) is detected by an optical sensor, it is necessary to separately provide the position determination means in the processing step of the recording medium, leading to an increase in the number of processing steps and cost increase of the recording medium. It will

  Also, in the case of making the optical sensor movable, the provision of the movable mechanism leads to an increase in the size and cost of the transport apparatus, and the arrangement of the optical sensor depends on the user's operation, which is usability It is not preferable from the viewpoint of In addition, if recording on the recording medium is performed while the optical sensor is not properly disposed, the leading end of the recording medium can not be properly detected, which may cause a problem such as a shift in the recording position.

  Furthermore, in the case where a plurality of optical sensors are arranged in parallel in the width direction, for example, when the front end in the transport direction of the triangular recording medium is the apex of the triangle, the apex of the triangle is necessarily on the optical axis of the optical sensor. Does not necessarily arrive, resulting in detection delay of the leading edge of the recording medium. When such a detection delay of the tip occurs, it is possible to cope with this by advancing the timing of recording start on the recording medium by the detection delay. However, in this case, it is necessary to provide a distance between the optical sensor and the recording head to adjust the timing of the start of recording, and the larger the detection delay of the leading edge, the larger the size of the apparatus.

  Under such circumstances, Patent Document 1 discloses a configuration in which a detection area is efficiently extended by arranging a plurality of image sensors in a planar and zigzag manner. By detecting the leading end of the recording medium with a sensor having the configuration of Patent Document 1, the leading end of the recording medium of any shape can be detected.

JP, 2008-076377, A

  However, according to Patent Document 1, in the case where it is only necessary to detect that the recording medium to be conveyed has reached the position where the optical sensor is provided, the optical sensor does not have to be widened. There is a problem that the cost increases because the number of is too large.

  An object of the present invention is to provide a recording medium transport apparatus and an image recording apparatus capable of suppressing the cost by detecting the arrival of recording media of different shapes without increasing the number of optical sensors.

  The recording medium transport apparatus according to the present invention comprises a transport means for transporting the recording medium, a plurality of light emitting units for emitting light toward the transport path of the recording medium transported by the transport means, and emission from the plurality of light emitting units. And detecting the arrival of the recording medium conveyed by the conveyance unit to the light receiving unit based on the plurality of light receiving units that receive the received light through the conveyance path and the light amounts received by the plurality of light receiving units. Control means, and the plurality of light emitting units and the plurality of light receiving units include a recording medium in which an optical axis of the plurality of light emitting units and an optical axis of the plurality of light receiving units are transported by the transport unit. It is characterized in that it is provided so as to be alternately line-shaped in a width direction intersecting the transport direction.

  The image recording apparatus according to the present invention comprises a transport means for transporting a recording medium, a plurality of light emitting units for emitting light toward the transport path of the recording medium transported by the transport means, and the plurality of light emitting units Control for detecting the arrival of the recording medium conveyed by the conveyance unit to the light receiving unit, based on the plurality of light receiving units receiving light through the conveyance path and the light amounts received by the plurality of light receiving units Means, and an image recording means for recording an image on a recording medium based on the detection result of the control means, the plurality of light emitting units and the plurality of light receiving units being an optical axis of the plurality of light emitting units and It is characterized in that the optical axes of the plurality of light receiving portions are alternately arranged in a line shape in a width direction intersecting a conveyance direction of the recording medium conveyed by the conveyance means.

  According to the present invention, cost can be suppressed by detecting the arrival of recording media of different shapes without increasing the number of optical sensors.

FIG. 1 is a schematic view of an image recording apparatus according to Embodiment 1 of the present invention. FIG. 2 is a block diagram of a part of the configuration of the image recording apparatus according to Embodiment 1 of the present invention. It is a flowchart which shows the sensor selection process which concerns on Embodiment 1 of this invention. It is a figure which shows the transmittance | permeability of the recording medium conveyed in the image recording apparatus which concerns on Embodiment 1 of this invention. FIG. 6 is a flow chart showing a recording operation on a cut sheet in the image recording apparatus according to Embodiment 1 of the present invention. FIG. 6 is a flowchart showing a recording operation on roll paper in the image recording apparatus according to Embodiment 1 of the present invention. It is a schematic diagram which shows arrangement | positioning of the optical sensor of the image recording apparatus which concerns on Embodiment 1 of this invention. It is a figure for demonstrating the front-end | tip detection process which the conventional image recording apparatus performs. It is a figure which shows the timing which detects the front-end | tip of the recording medium by the conventional image recording apparatus. It is a figure for demonstrating the front-end | tip detection process which the image recording apparatus which concerns on Embodiment 1 of this invention performs. FIG. 7 is a diagram showing timing of detecting the leading end of the recording medium by the image recording apparatus according to Embodiment 1 of the present invention. It is a flowchart which shows the sensor selection process which concerns on Embodiment 2 of this invention.

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

Embodiment 1
<Configuration of Image Recording Apparatus>
The configuration of the image recording apparatus 1 according to Embodiment 1 of the present invention will be described in detail with reference to FIGS. 1 and 2.

  The image recording apparatus 1 includes a platen 104, a recording head 105, a carriage 106, a conveyance roller 108, a main control substrate 109, an optical sensor 110, and a conveyance unit 214.

  A platen 104 as a conveyance path supports the recording medium 103.

  The recording head 105 as an image recording unit can move up and down by driving a head raising and lowering motor (not shown) while maintaining a predetermined distance from the platen 104. In the recording head 105, an ejection port for ejecting ink is formed on the surface facing the platen 104. The recording head 105 discharges ink from the discharge port toward the recording medium 103 under the control of the main control substrate 109, and an image corresponding to the width direction crossing the recording medium 103 conveyance direction of the recording head 105 is displayed. , Recording on the recording medium 103. The print head 105 is configured of four independent print heads that eject four color inks, for example, black K, cyan C, magenta M, and yellow Y.

  The carriage 106 detachably mounts the recording head 105, and is fixed to face the platen 104.

  The conveyance roller 108 as a conveyance unit is rotated by the driving force of the conveyance motor 107 of the conveyance unit 214 to convey the recording medium 103 in the conveyance direction.

  The main control board 109 executes image data processing, recording data generation and transfer processing, or drive control processing of the entire apparatus including the recording head 105, the conveyance motor 107 and the optical sensor 110, etc. Take control of the whole.

  The optical sensor 110 is a transmission type sensor, and is positioned upstream of the carriage 106 in the conveyance direction of the recording medium 103, and is opposed to the recording medium 103 and the platen 104 to the plurality of light emitting elements 101 and the plurality of light receiving elements 102. And have. The light emitting element 101 and the light receiving element 102 are disposed opposite to each other across a conveyance path on which the recording medium 103 such as label paper is conveyed, and the optical axis of the light emitting element 101 and the optical axis of the light receiving element 102 are in the width direction Are arranged alternately along the line.

  The light emitting element 101 as a light emitting unit faces the recording medium 103 and the platen 104 and emits light toward the conveyance path of the recording medium 103.

  The light receiving element 102 as a light receiving unit receives the light emitted from the light emitting element 101 via the recording medium 103 and the platen 104 or via the platen 104. The light receiving element 102 outputs a detection signal corresponding to the amount of received light to the ASIC 204 via the sensor drive circuit 212.

  The distance in the height direction between the light emitting element 101 and the light receiving element 102 can be determined in accordance with the performance or arrangement interval of the light emitting element 101 and the light receiving element 102.

  The transport unit 214 transports the recording medium 103 under the control of the main control substrate 109, and includes a transport motor 107 for rotating the transport roller 108, and an encoder 210 arranged to follow the transport of the recording medium 103. Is equipped.

<Configuration of main control board>
The configuration of the main control substrate 109 according to the first embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2.

  The main control board 109 has a CPU 201, a ROM 202, a RAM 203, an ASIC 204, a RAM 205, a sensor drive circuit 212, and an actuator drive circuit 217.

  The CPU 201 controls the entire image recording apparatus 1 including the ASIC 204 based on a control program stored in the ROM 202, various history information of the image recording apparatus 1, or a command signal or image information stored in the RAM 203.

  The ROM 202 is connected to the CPU 201 via the ROM bus 215, and stores control programs, various kinds of history information of the image recording apparatus 1, and the like.

  The RAM 203 stores command signals and image information received by the CPU 201 from the host PC 206.

  An ASIC 204 as control means is connected to the CPU 201 via the ROM bus 215 and operates under the control of the CPU 201.

  Specifically, the ASIC 204 receives each color image data from the CPU 201, generates print data, and stores the generated print data in the RAM 205. The ASIC 204 controls the operation of the actuator drive circuit 217 to control the drive of the transport motor 107 mounted on the transport unit 214. The ASIC 204 controls the operation of the sensor drive circuit 212 to control the drive of the light receiving element 102 and the light emitting element 101 of the optical sensor 110.

  Further, the ASIC 204 executes sensor selection processing described later before image recording, and selects the light receiving element 102 that detects the arrival of the recording medium 103 at the time of image recording. The ASIC 204 converts the detection signal input from the sensor drive circuit 212 from analog signal format to digital signal format, and outputs the converted signal to the CPU 201. The ASIC 204 detects the leading edge of the recording medium 103 in the transport direction based on the detection signal input from the sensor drive circuit 212, thereby detecting the arrival of the recording medium 103 on the optical sensor 110.

  Further, the ASIC 204 determines the state of the recording medium 103 based on the electrical signal input from the encoder 210 and the detection signal input from the sensor drive circuit 212. The ASIC 204 transfers the recording data stored in the RAM 205 to the recording head 105 based on the determination result of the state of the recording medium 103 and causes the recording medium 103 to record an image. The ASIC 204 monitors the operation of various ink tanks and actuators (not shown) and the entire image recording apparatus 1 such as environmental conditions.

  The RAM 205 stores the recording data generated by the ASIC 204.

  The sensor drive circuit 212 operates the light emitting element 101 and the light receiving element 102 of the optical sensor 110 under the control of the ASIC 204, and outputs a detection signal input from the light receiving element 102 to the ASIC 204.

  The actuator drive circuit 217 controls the drive of the conveyance motor 107 under the control of the ASIC 204.

<Sensor selection processing>
The sensor selection process according to the first embodiment of the present invention will be described in detail with reference to FIGS. 3 and 4.

  The sensor selection process shown in FIG. 3 is performed before image recording.

  First, the CPU 201 sets in advance in the ASIC 204 a determination criterion for determining the presence or absence of the recording medium 103 (S1).

  Next, the ASIC 204 controls the operation of the actuator drive circuit 217 under the control of the CPU 201 to drive the transport motor 107, thereby transporting and moving the recording medium 103 to the sensor detection position where the optical sensor 110 is disposed. (S2).

  Next, the ASIC 204 controls the operation of the actuator drive circuit 217 to stop the transport motor 107 and stop the transport of the recording medium 103.

  Next, the ASIC 204 controls the operation of the sensor drive circuit 212 to start the operation of the light emitting element 101 and the light receiving element 102 of the optical sensor 110.

  Next, the ASIC 204 determines the presence / absence of arrival of the recording medium 103 based on the determination reference set in step S 1 and a detection signal according to the amount of light received by the light receiving element 102 input to the sensor drive circuit 212. (S3).

  Here, when the ASIC 204 transports the label sheet, the ASIC 204 responds to the difference between the transmittance of the backing (separator) and the transmittance of the top paper (label) as the recording medium 103 stuck on the backing. The arrival of the upper sheet is detected based on the detection signal from the light receiving element 102.

  Specifically, as shown in FIG. 4A, the transmittance T1 of the backing sheet is higher than the transmittance T2 of the upper sheet (T1> T2). Therefore, as shown in FIG. 4B, the light receiving element 102 receives more light from the light emitting element 101 when there is a mount between the light emitting element 101 and the light receiving element 102 than when there is an upper sheet. To output a high level detection signal. The ASIC 204 detects a timing at which the level of the detection signal from the light receiving element 102 falls below a predetermined threshold, and determines that the leading edge of the upper sheet has reached at this timing. Further, the ASIC 204 detects timing when the level of the detection signal from the light receiving element 102 becomes equal to or higher than a predetermined threshold, and determines that the trailing edge of the upper sheet has arrived at this timing.

  Next, the ASIC 204 determines whether or not the determination of the presence or absence of the arrival of the recording medium 103 has ended for all the light receiving elements 102 of the optical sensor 110 (S4).

  The ASIC 204 controls the operation of the sensor drive circuit 212 to switch to the next light emitting element group 101 and the light receiving element 102 to start output when the determination is not completed for all the light receiving elements 102 (S4: No) (S5) Return to the process of step S4.

  On the other hand, the ASIC 204 determines the number of the light receiving elements 102 that detect the recording medium 103 and the position of the light receiving element 102 stored in advance in the width direction when the determination is completed for all the light receiving elements 102 (S4: Yes). (S6).

  Next, the ASIC 204 determines whether the number of light receiving elements 102 confirmed is plural (S7).

  When the number of light receiving elements 102 confirmed is one (S7: No), the ASIC 204 selects the light receiving element 102 that has detected the recording medium 103 (S8), and ends the sensor selection process.

  On the other hand, the ASIC 204 determines whether the number is equal to the number of all the light receiving elements 102 of the optical sensor 110 when the number of the light receiving elements 102 confirmed is plural (S7: Yes) (S9) ).

  When the number of light receiving elements 102 confirmed is equal to the number of all light receiving elements 102 (S9: Yes), the ASIC 204 selects a predetermined light receiving element 102 disposed at a predetermined reference position (S10). ), End the sensor selection process.

  On the other hand, when the number of light receiving elements 102 confirmed is not equal to the number of all light receiving elements 102 (S9: No), the ASIC 204 specifies a part of the light receiving elements 102 confirmed and narrows down the light receiving elements 102. (S11).

  Next, the ASIC 204 determines whether the number of light receiving elements 102 narrowed down is the same as the number of light receiving elements 102 narrowed down last time (S12).

  The ASIC 204 returns to the process of step S2 when the number of light receiving elements 102 narrowed down is not the same as the number of light receiving elements 102 narrowed down last time (S12: No).

  On the other hand, when the number of light receiving elements 102 narrowed down is the same as the number of light receiving elements 102 narrowed down last time (S12: Yes), the ASIC 204 is a light receiving element positioned at the center in the width direction 102 is selected (S13). After that, the ASIC 204 ends the sensor selection process. By performing such sensor selection processing, it is possible to select the light receiving element 102 in the optimum arrangement even in the recording medium 103 of any shape.

  As described above, the image recording apparatus 1 is used to detect the recording medium 103 at the time of image recording from among the plurality of light receiving elements 102 based on the detection result of the light receiving element 102 when the above-described sensor selection processing is performed. The light receiving element 102 is selected.

<Operation of Image Recording Device>
The operation of the image recording apparatus 1 according to the first embodiment of the present invention will be described in detail.

  First, the operation when recording an image on the recording medium 103 which is a sheet of JIS standard such as A3 or A4 or a cut sheet such as a business card or postcard will be described in detail with reference to FIG.

  First, the ASIC 204 controls the operation of the actuator drive circuit 217 under the control of the CPU 201 that has received the image data from the host PC 206 to drive the conveyance motor 107 to feed the recording medium 103 (S21).

  Next, the ASIC 204 executes the above sensor selection process and executes the leading edge detection process using the selected light receiving element 102, thereby detecting the leading edge of the recording medium 103 (S22). The tip detection process will be described later.

  Next, the ASIC 204 sets a recording start position (S23).

  Next, the ASIC 204 determines whether or not a predetermined time until the recording medium 103 is transported to the set recording start position has elapsed based on the electrical signal input from the encoder 210 (S24).

  The ASIC 204 repeats the operation of step S24 when the predetermined time has not elapsed (S24: No).

  On the other hand, when the predetermined time has passed (S24: Yes), the ASIC 204 controls the operation of the recording head 105 and starts recording an image on the recording medium 103 (S25).

  Next, the ASIC 204 determines whether the rear end of the recording medium 103 is detected by the light emitting element 101 and the light receiving element 102 (S26).

  When the ASIC 204 does not detect the rear end of the recording medium 103 (S26: No), the operation of step S26 is repeated.

  On the other hand, when the ASIC 204 detects the rear end of the recording medium 103 (S26: Yes), the ASIC 204 controls the operation of the recording head 105 to stop the recording of the image on the recording medium 103 (S27).

  Next, the ASIC 204 determines whether the CPU 201 receives the image data of the next page from the host PC 206 (S28).

  If the CPU 201 receives image data of the next page from the host PC 206 (S28: Yes), the ASIC 204 returns to the operation of step S21.

  On the other hand, when the CPU 201 does not receive the image data of the next page from the host PC 206 (S28: No), the ASIC 204 controls the operation of the actuator drive circuit 217 to stop the drive of the transport motor 107 (S29). End the operation.

  Subsequently, an operation when recording an image on the recording medium 103 which is roll paper such as label paper will be described in detail with reference to FIG.

  First, under the control of the CPU 201 which has received image data from the host PC 206, the ASIC 204 executes the above sensor selection process and executes the leading edge detection process using the selected light receiving element 102, whereby the leading edge of the recording medium 103 is detected. It detects (S31). The tip detection process will be described later.

  Next, the ASIC 204 sets a recording start position (S32).

  Next, the ASIC 204 determines whether or not a predetermined time until the recording medium 103 is transported to the set recording start position has elapsed based on the electrical signal input from the encoder 210 (S33).

  The ASIC 204 repeats the operation of step S33 when the predetermined time has not elapsed (S33: No).

  On the other hand, when the predetermined time has elapsed (S33: Yes), the ASIC 204 controls the operation of the recording head 105 and starts recording an image on the recording medium 103 (S34).

  Next, the ASIC 204 determines whether the CPU 201 receives image data of the next page from the host PC 206 (S35).

  If the CPU 201 receives image data of the next page from the host PC 206 (S35: Yes), the ASIC 204 returns to the operation of step S31.

  On the other hand, the ASIC 204 determines whether the rear end of the recording medium 103 has been detected by the light emitting element 101 and the light receiving element 102 when the CPU 201 has not received the image data of the next page from the host PC 206 (S35: No). (S36).

  When the ASIC 204 does not detect the rear end of the recording medium 103 (S36: No), the operation of step S36 is repeated.

  On the other hand, when the ASIC 204 detects the rear end of the recording medium 103 (S36: Yes), the ASIC 204 controls the operation of the recording head 105 to stop the recording of the image on the recording medium 103 (S37).

  Next, the ASIC 204 controls the operation of the actuator drive circuit 217 to stop the drive of the conveyance motor 107 (S38), and ends the operation.

<Tip detection process>
The tip detection process according to the first embodiment of the present invention will be described in detail with reference to FIGS. 7 to 11.

  The light emitting elements 101 and the light receiving elements 102 of the optical sensor 110 are, as shown in FIG. 7, shifted by half a pitch between the optical axes Q1 of the plurality of light emitting elements 101 and the optical axes Q2 of the plurality of light receiving elements 102 in the width direction. They are arranged opposite to each other in a line-like manner. The light receiving element 102 is preferably arranged such that the optical axis Q2 is positioned at the center of the distance between the optical axes Q1 of two light emitting elements 101 adjacent in the width direction. The light receiving element 102 is preferably arranged to receive light emitted from two adjacent light emitting elements 101 in the width direction with an equal amount of light. The ASIC 204 detects the boundary between the upper sheet and the backing sheet at the timing when the conveyed object passes on the line on which the light emitting element 101 and the light receiving element 102 are arranged.

  The optical sensor 110 configured as described above is, for example, an upper sheet of label paper having an upper sheet as a recording medium 103 having a tip shape not parallel to the width direction, and a mount on which the upper sheet is attached. Detect the tip. At this time, the label sheet is transported in parallel to the transport direction while one end in the width direction of the backing sheet abuts against the reference wall H disposed parallel to the transport direction.

  Here, with regard to the case where the label paper whose upper paper shape is a triangle as the recording medium 103 is conveyed in the direction in which the leading edge becomes one vertex of the triangle, referring to FIG. 8 to FIG. It demonstrates, comparing with the past. In FIGS. 9 and 11, the conveyance direction of the upper sheet is the left direction.

  In the conventional image forming apparatus, as shown in FIG. 8, the light emitting elements HS0, HS1 and HS2 and the light receiving elements JS0, JS1 and JS2 are disposed opposite to each other. In such a conventional image forming apparatus, the light emitting elements HS0, HS1 and HS2 and the light receiving elements JS0, JS1 and JS2 are arranged at equal intervals of the pitch P in the width direction. At this time, the distance between detection points in the width direction by the optical sensor is the same as the pitch P.

  For example, when the leading edge of the upper sheet is conveyed to the center of the distance in the width direction between the light receiving element JS0 and the light receiving element JS1, after the leading end of the upper sheet reaches between the light receiving element JS0 and the light receiving element JS1 The detection delay distances D0 and D1 are generated until the upper sheet is detected. The detection delay distances D0 and D1 can be obtained from equation (1), where the vertex angle of the triangle is 2θ.

D0 = D1 = P / 2 / tan θ (1)
Specifically, as shown in FIG. 9, when the pitch P is 8.8 mm and the angle 2θ of the apex of the top of the upper sheet is 60 ° (= equilateral triangle), detection is performed according to equation (1). The delay distances D0 and D1 are about 7.6 mm. From this, the conventional image recording apparatus detects the upper sheet at the timing when the leading end of the upper sheet passes by about 7.6 mm in the transport direction from the arrangement position of the optical sensor. Therefore, in the conventional image recording apparatus, it is necessary to advance the time to start recording on the upper sheet by the time obtained by dividing about 7.6 mm by the transport speed from the time to detect the upper sheet. This indicates that the distance between the optical sensor and the recording head can not be shorter than about 7.6 mm.

  On the other hand, the light emitting elements HS10, HS11, HS12 and the light receiving elements JS10, JS11, JS12 of the present embodiment are alternately arranged at equal intervals at the pitch P in the width direction, as shown in FIG. There is. At this time, the distance between detection points in the width direction by the optical sensor is half the pitch P (P / 2).

  For example, when the leading edge of the upper sheet is conveyed to the center of the distance in the width direction between the light receiving element JS10 and the light receiving element JS11, the leading end of the upper sheet reaches between the light receiving element JS10 and the light receiving element JS11. The detection delay distances D2 and D3 are generated until the upper sheet is detected. The detection delay distances D2 and D3 can be obtained by the equation (2), assuming that the vertex angle of the triangle is 2θ.

D2 = D3 = P / 4 / tan θ (2)
From the above equations (1) and (2), in the present embodiment, the detection delay distance of the front end of the upper sheet can be reduced to half of the conventional case.

  Specifically, as shown in FIG. 11, when the pitch P is 8.8 mm and the angle 2θ of the top of the top of the upper sheet is 60 ° (= equilateral triangle), detection is performed according to equation (2). The delay distances D2 and D3 are about 3.8 mm. From this, the image recording apparatus according to the present embodiment detects the upper sheet at the timing when the leading end of the upper sheet passes by about 3.8 mm in the transport direction from the arrangement position of the optical sensor 110. Therefore, in the image recording apparatus according to the present embodiment, it is necessary to advance the time to start recording on the upper sheet by a time obtained by dividing about 3.8 mm by the transport speed than the time to detect the upper sheet. This indicates that the distance between the optical sensor and the recording head can not be shorter than about 3.8 mm.

  From the above, since the detection delay distance of the front end of the upper sheet in the present embodiment is suppressed to about 3.8 mm, which is about half that of the conventional one, the distance between the optical sensor and the recording head is 7.6 mm or more. It can be relaxed to 8 mm or more, and the device can be miniaturized.

  As described above, in the present embodiment, the plurality of light emitting elements 101 of the optical sensor 110 are alternately arranged so that the optical axes of the plurality of light emitting elements 101 and the optical axes of the plurality of light receiving elements 102 are linear in the width direction. And a plurality of light receiving elements 102 are provided. Thus, the cost can be suppressed by detecting the arrival of recording media of different shapes without increasing the number of optical sensors.

Second Embodiment
The configuration of the image recording apparatus according to the second embodiment of the present invention is the same as that of FIG. 1 and FIG.

<Sensor selection processing>
The sensor selection process according to the second embodiment of the present invention will be described in detail with reference to FIG.

  Parts in FIG. 12 identical to those in FIG. 3 are assigned the same codes as in FIG. 3 and their explanations are omitted.

  The ASIC 204 determines whether the number of narrowed light receiving elements 102 is even (S41: Yes) if the number of narrowed light receiving elements 102 is the same as the number of light receiving elements 102 narrowed last time (S12: Yes). ).

  When the number of narrowed light receiving elements 102 is an odd number (S41: No), the ASIC 204 selects a single light receiving element 102 positioned at the center in the width direction of the narrowed light receiving elements 102 (S42) End the sensor selection process.

  On the other hand, when the number of narrowed light receiving elements 102 is an even number (S41: Yes), the ASIC 204 selects two light receiving elements 102 positioned at the center in the width direction among the narrowed light receiving elements 102 (S43) .

  Next, the ASIC 204 controls the sensor drive circuit 212 to increase the light quantity of the light emitting element 101 disposed between the two selected light receiving elements 102, and turns off the other light emitting elements 101 (S44). ), End the sensor selection process.

  The ASIC 204 may reduce the light amounts of the other light emitting elements 101 in the process of step S44, and relatively increase the intensity of the light received by the two light receiving elements 102 selected in the process of step S43. Processing can be performed.

  As described above, in the present embodiment, the amount of light of the light emitting element 101 located at the tip of the recording medium 103 is increased, and the amount of light of the other light emitting elements 101 is suppressed. The light amount of the light emitting element 101 located is relatively increased. Thus, in addition to the effects of the first embodiment, the accuracy of detection of the leading end of the recording medium 103 can be improved.

  The present invention is not limited to the above embodiment, and it goes without saying that various modifications can be made without departing from the scope of the invention.

  Specifically, although the light receiving element is provided to have the optical axis at the center of the distance between the optical axes of the adjacent light emitting elements in the first embodiment and the second embodiment, the optical axes of the adjacent light emitting elements are provided. The light receiving element may be provided to have an optical axis other than the center of the distance between the two.

  In the first and second embodiments, the light emitting element 101 is disposed on the recording surface side of the recording medium 103, and the light receiving element 102 is disposed on the back surface side of the recording surface of the recording medium 103. The light receiving element may be arranged reverse to this.

  Although the inkjet type image recording apparatus is used in the first and second embodiments, the present invention may be applied to a thermal transfer type, thermal type or dot impact type image recording apparatus.

Reference Signs List 1 image recording apparatus 101 light emitting element 102 light receiving element 103 recording medium 105 recording head 107 conveyance motor 109 main control substrate 110 optical sensor 201 CPU
204 ASIC
212 sensor drive circuit 217 actuator drive circuit

Claims (9)

Transport means for transporting the recording medium;
A plurality of light emitting units for emitting light toward the transport path of the recording medium transported by the transport means;
A plurality of light receiving units for receiving the light emitted from the plurality of light emitting units through the conveyance path;
A control unit that detects the arrival of the recording medium conveyed by the conveyance unit at the light reception unit, based on the amount of light received by the plurality of light reception units;
Have
The plurality of light emitting units and the plurality of light receiving units are
The optical axes of the plurality of light emitting units and the optical axes of the plurality of light receiving units are alternately arranged in a line in the width direction intersecting the conveyance direction of the recording medium conveyed by the conveyance unit.
A recording medium conveyance device characterized by the above. The light receiving unit is
The light emitted from the two light emitting units adjacent in the width direction is received with the same light amount.
The recording medium conveying apparatus according to claim 1, The light receiving unit is
It has an optical axis at the center of the distance between the optical axes of two adjacent light emitting units in the width direction,
The recording medium transport apparatus according to claim 1 or 2, wherein The control means
Before image recording, a selection process of selecting the light receiving unit for detecting the arrival at the time of image recording from among the plurality of light receiving units is executed based on the detection result when the arrival is detected.
The recording medium conveyance device according to any one of claims 1 to 3, characterized in that: The control means
In the case where the detection result is that the arrival is detected by all of the plurality of light receiving units in the selection process, the predetermined light receiving unit is selected.
The recording medium conveyance device according to claim 4, The control means
When it is the detection result that the reaching is detected by a part of the plurality of light receiving parts in the selection process, the light receiving part at the center in the width direction of the part of the light receiving parts is selected ,
The recording medium transport apparatus according to claim 4 or 5, wherein The control means
When it is the detection result in which the reaching is detected by a part of the plurality of light receiving parts in the selection process, the number of the light receiving parts is an odd number when the number of the light receiving parts is an odd number Select the single single light receiving unit at the center in the width direction of the above, and when the number of the light receiving units of the part is an even number, the center in the width direction of the light receiving units of the part Select two of the light receiving units,
The recording medium conveyance device according to any one of claims 4 to 6, characterized in that The control means
When the number of the light receiving portions is an even number, the light amount of the light emitting portion positioned between the two selected light receiving portions is relatively increased relative to the light amount of the other light emitting portions.
The recording medium transport apparatus according to claim 7, wherein Transport means for transporting the recording medium;
A plurality of light emitting units for emitting light toward the transport path of the recording medium transported by the transport means;
A plurality of light receiving units for receiving the light emitted from the plurality of light emitting units through the conveyance path;
A control unit that detects the arrival of the recording medium conveyed by the conveyance unit at the light reception unit, based on the amount of light received by the plurality of light reception units;
An image recording unit that records an image on a recording medium based on the detection result of the control unit;
Have
The plurality of light emitting units and the plurality of light receiving units are
The optical axes of the plurality of light emitting units and the optical axes of the plurality of light receiving units are alternately arranged in a line in the width direction intersecting the conveyance direction of the recording medium conveyed by the conveyance unit.
An image recording apparatus characterized by

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