JP2007055187A - Image recording device and image recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly precisely control an image recording position to recording media even though the colors of the recording media and the conveying media of the conveying mechanism mounting and conveying the recording media approximate to each other. <P>SOLUTION: The light amount detecting signal output from a line sensor 33 detecting the transmitted light (the detected light) of the recording media 21 is validated at a timing when the detecting hole 39 of the belt of the conveying mechanism 20 arrives at the lower side of the line sensor 33, the continuous position information of the edge in one side end of the recording media 21 is obtained based on the validated light amount detecting signal, and the discharging positions of the respective inks of respective colors of K, C, M, Y discharged from the respective inkjet heads 29 to 32 of an image recording section 28 are controlled. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image recording apparatus that performs image recording by landing ink on a recording medium conveyed by, for example, a conveyance mechanism, and relates to an image recording apparatus and an image recording method that improve the accuracy of a recording position on the recording medium.

FIG. 20 is a configuration diagram of a portion related to paper edge detection in the image forming apparatus disclosed in Patent Document 1. The transfer belt 3 is stretched between the two rollers 1 and 2. The sheet 4 is adsorbed on the transfer belt 3, and the sheet 4 is conveyed in the conveyance direction A by the movement of the transfer belt 3. On the upstream side of the transfer belt 3, a line sensor 5 that detects the leading edge and the left and right edges of the paper 4 is provided. The detection output of the line sensor 5 is sent to the paper edge detection 6.
When the sheet 4 is supplied from the upstream side of the transfer belt 3, the sheet 4 is adsorbed on the transfer belt 3, and the sheet 4 is conveyed in the conveyance direction A by the movement of the transfer belt 3. The line sensor 5 detects the leading edge and the left and right edges of the conveyed paper 4. The image formation on the sheet 4 is performed at timings corresponding to the positions of the leading edge and the left and right edges of the sheet 4 detected by the line sensor 5, K (black), C (cyan), M (magenta), Y (yellow). ) Image formation of each color component is performed. The sheet 4 on which image formation has been performed is carried out of the apparatus and is loaded, for example, in a discharge tray.

FIG. 21 is a schematic configuration diagram of an image forming apparatus disclosed in Patent Document 2. An intermediate transfer material 8 is stretched between the rollers 7a, 7b, 7c. A slit 9 is provided in the non-image area of the intermediate transfer material 8, and a registration sensor 10 is provided above the slit 9. A reflection plate 11 is installed on the extension of the registration sensor 10 and the slit 9. The registration sensor 10 is for synchronizing the overlay of each color of K, C, M, and Y, for example, and a registration pattern formed for each color of K, C, M, and Y in a non-image area. read. The registration sensor 10 detects reflected light from the reflection plate 11 when the slit 9 of the intermediate transfer material 8 passes, and determines the contamination of the registration sensor 10 from the amount of reflected light. A roller 7d is attached to the roller (transfer roller) 7c, and the transfer body 12 is sent between the rollers 7c and 7d.
The intermediate transfer material 8 is in contact with the respective photosensitive drums of K, C, M, and Y, and receives a visible image transferred from the photosensitive drums. The visible image transferred to the intermediate transfer material 8 is transferred to the transfer body 12 as a color visible image by the conveyance of the intermediate transfer material 8.
JP-A-10-186951 JP 2003-307900 A

  Since the line sensor 5 in Patent Document 1 is provided above the transfer belt 3, it is directly affected by the surface condition of the transfer belt 3. For example, if foreign matters such as ink stains or paper pieces adhere to the transfer belt 3, the line sensor 5 may erroneously detect the ink stains or foreign matter on the transfer belt 3 as the paper 4. If the paper 4 has a color similar to the color of the transfer belt 3 or has a reflectance equivalent to the reflectance of the transfer belt 3, the line sensor 5 is connected to the transfer belt 3 and the paper 4. And the paper 4 on the transfer belt 3 cannot be detected. For this reason, the position of the image formed on the paper 4 cannot be determined with high accuracy.

  Since the registration sensor 10 in Patent Document 2 is provided above the non-image area of the intermediate transfer material 8, it does not detect the transfer body 12 itself. For this reason, it is impossible to increase the detection accuracy of the end portion such as the front end of the transfer body 12, and when the image forming area on the intermediate transfer material 8 to which the image is transferred is stained with ink or the like, the registration sensor 10 May erroneously detect a registration pattern and dirt. Further, although it is possible to correct dirt or the like in the detection area of the registration sensor 10, if the intermediate transfer material 8 itself is dirty, the registration pattern cannot be accurately detected and may be erroneously detected. .

  Therefore, the present invention provides an image recording apparatus and an image recording apparatus capable of controlling the image recording position with respect to the recording medium with high accuracy even when the colors of the recording medium and the conveying member of the conveying mechanism for placing and conveying the recording medium are approximate. It aims to provide a method.

  In order to solve the above problems, an image recording apparatus of the present invention includes a transport mechanism that transports a recording medium by moving a transport member on which the recording medium is placed, and a transport amount of the recording medium that is transported by the transport mechanism. An image recording apparatus having a conveyance information generation unit that generates conveyance information and an image recording unit that records an image on a recording medium conveyed by a conveyance mechanism, the conveyance direction of the recording medium with respect to a conveyance member A plurality of holes provided in the recording medium, and upstream of the image recording unit in the recording medium conveyance direction. And a light detection unit, a medium detection unit that detects light emitted from the light projection unit and detection light based on the light, and a control unit that controls at least the transport mechanism, the image recording unit, and the medium detection unit. To do.

The image recording method of the present invention is an image recording method for recording an image on a recording medium in a process of placing the recording medium on a conveying member and conveying the recording medium by moving the conveying member,
When it is determined whether or not a plurality of detection holes provided in the conveying member have reached the lower side of the medium detection unit for detecting the recording medium, and the recording medium is detected at the timing when the detection hole reaches the lower side of the medium detection unit A position at which the detection signal output from the medium detection unit is validated, position information of at least one side end of the recording medium is obtained based on the validated detection signal, and an image is recorded on the recording medium based on the position information. It is characterized by controlling.

  The present invention relates to an image recording apparatus and an image recording method capable of controlling an image recording position with respect to a recording medium with high accuracy even when the colors of the recording medium and a conveying member of a conveying mechanism for placing and conveying the recording medium are approximate. Can provide.

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is an external configuration diagram of an image recording apparatus. The transport mechanism 20 sucks and holds the recording medium 21 supplied from the supply side and transports the recording medium 21 in the transport direction B. The transport mechanism 20 is provided for driving and provided at both ends of the platen 22 so as to be rotatable. It has a roller 23 and a driven roller 24, a tension roller 25, and a belt 26 as a conveying member stretched around these rollers 23-25. A driving motor 27 is connected to the driving roller 23. When the drive motor 27 is driven, the rotation of the drive motor 27 is transmitted to the drive roller 23, whereby the belt 26 performs a conveying operation.

An image recording unit 28 is provided above the transport mechanism 20. The image recording unit 28 performs color image recording on the recording medium 21 conveyed by the conveyance mechanism 20, and includes inkjet heads 29 to 32 for K, C, M, and Y colors. These ink jet heads 29 to 32 eject inks of K, C, M, and Y, respectively.
A line sensor 33 serving as a medium detection unit is provided above the transport mechanism 20 and upstream of the image recording unit 28. In the detection area of the line sensor 33 and in the platen 22 vertically below the line sensor 33, a line-shaped illumination light (hereinafter referred to as a line illumination light) L ₁ is projected facing the line sensor 33. A light projecting unit 34 is provided. However, the line sensor 33, when blocked illumination light L ₁ with transmitted light (detection light) and a belt 26 that has passed through at least a recording medium 21 when it is projected line illumination light L ₁ from the light projecting unit 34 The belt surface or the like is detected, and a light amount detection signal corresponding to these light amounts is output. Based on the light amount detection signal output from the line sensor 33, the side edge information generation unit 61 (to be described later) detects both side edge positions of the recording medium 21. The line sensor 33 has a line length longer than the maximum medium width W _MAX of the recording medium 21. The line sensor 33 includes, for example, two line sensors, for example, a left line sensor 33a and a right line sensor 33b that are connected in a single line, and have a line length longer than the maximum medium width W _MAX of the recording medium 21. Secured. If the line sensor 33 has a line length longer than the maximum medium width W _MAX of the recording medium 21, one line sensor 33 may be used. For example, a general contact image sensor is used as the line sensor 33.

2 to 4 are configuration diagrams around the installation of the line sensor 33 in the transport mechanism 20, FIG. 2 is a perspective view showing the structure of the platen 22, FIG. 3 is a top view showing the structure of the platen 22, and FIG. The layout of the sensor 33 and the platen 22 is shown. A rectangular opening 35 that forms a light projecting unit 34 is provided upstream of the image recording unit 28 in the platen 22. The opening 35 is formed in a line shape in the direction perpendicular to the conveyance direction B of the recording medium 21. The opening 35 is formed to have a line length W ₁ longer than the maximum medium width W _MAX of the recording medium 21 and a predetermined width W ₂ . The opening 35 communicates with a light guide hole 36 provided in the platen 22. The light guide hole 36 is formed so as to be directed downward in the vertical direction with respect to the surface of the platen 22 and bent at an angle of 90 °, for example. A line light source 37 is provided on the inner wall 36 a of the light guide hole 36. The line light source 37 outputs, for example, a white line illumination light L _1. In addition, a reflection surface 38 made of a flat mirror surface is provided at the bent portion of the light guide hole 36. The reflecting surface 38 is provided to be inclined by an angle θ (= 45 °) with respect to the optical axis of the line illumination light L ₁ output from the line light source 37. Accordingly, the line illumination light L ₁ output from the line light source 37 is reflected by the reflection surface 38 at an angle θ (= 45 °) and emitted from the opening 35.

A plurality of detection holes 39 formed in a rectangular shape are provided in the belt 26 at predetermined intervals in the direction perpendicular to the conveyance direction B. FIG. 5 shows the relationship between the size of each detection hole 39 provided in the belt 26 and the recording medium 21. In the apparatus, the arrangement direction (Y direction) of each of the inkjet heads 29 to 32 is set as a main scanning direction, and the conveyance direction B perpendicular to the main scanning direction is set as a sub scanning direction (X direction). Here, Ha represents the width in the main scanning direction of each detection hole 39, Hb represents the interval in the sub scanning direction of each detection hole 39, Hc represents the width in the scanning direction of each detection hole 39, and W _MAX represents the maximum medium of the recording medium 21. The width, W _MIN indicates the minimum medium width of the recording medium 21, and L _MIN indicates the minimum medium length of the recording medium 21.

Each detection hole 39 has a size and a positional relationship necessary for detecting the positions of both ends of the recording medium 21 by the line sensor 33. More specifically, the width Ha of each detection hole 39 in the main scanning direction is obtained by adding the widths of detection synchronization areas P ₁ and P ₂ (FIG. 8) to be described later to the maximum medium width W _MAX of the recording medium 21. It has more than width. That is, the main scanning direction width Ha is
Ha> W _MAX + 2 · wr (1)
wr: width of each detection synchronization area P ₁ , P ₂
The relationship is established.
Distance Hb in the sub-scanning direction of the detection holes 39 are arranged at intervals shorter than one third of the minimum medium length L _MIN of the recording medium 21. That is, the interval Hb in the sub-scanning direction is
Hb <(1/3) · L _MIN (2)
The relationship is established.
The width Hc in the sub-scanning direction of each detection hole 39 is longer than the distance that the recording medium 21 is conveyed during the reading time of one line of the line sensor 33. That is, the sub-scanning direction width Hc is
Hc> v _MAX · Trd (3)
v _MAX : Maximum conveyance speed by the belt 26,
Trd: Reading cycle of one line of the line sensor 33
The relationship is established. For example, if the reading cycle Trd of one line of the line sensor 33 is 1 msec and the maximum conveyance speed v _MAX by the belt 26 is 1000 mm / sec, the sub-scanning direction width Hc is the distance that the belt 26 moves during the 1 msec period. It is larger than 1 mm.

  FIG. 6 shows a configuration diagram of a transport system in the apparatus. The medium supply mechanism 40 is provided on the upstream side of the transport mechanism 20 and supplies the recording medium 21 to the transport mechanism 20 one by one. The medium supply mechanism 40 is provided with a medium storage unit 41 for stacking and storing a large number of recording media 21. A separation mechanism 42 and a pickup roller 43 are provided at the supply port of the medium storage unit 41. The separation mechanism 42 separates the recording medium 21 loaded on the top from the many recording media 21 stored in the medium storage unit 41. The pickup roller 43 picks up the recording medium 21 separated by the separation mechanism 42 one by one and supplies it to the downstream side. A registration roller pair 44 is provided on the downstream side of the medium storage unit 41. The registration roller pair 44 is for determining the leading edge alignment of the recording medium 21 and the feeding timing to the downstream transport mechanism 20.

A registration sensor 45 is provided between the medium storage unit 41 and the registration roller pair 44. The registration sensor 45 detects that the recording medium 21 has reached the registration roller pair 44 and outputs an arrival detection signal.
A top edge sensor 46 is provided between the registration roller pair 44 and the transport mechanism 20. The top edge sensor 46 detects the front end of the recording medium 21 supplied to the transport mechanism 20 and outputs a front end detection signal.

A suction roller 47 is provided in contact with the driven roller 24 in the transport mechanism 20 via a belt 26. The suction roller 47 brings the recording medium 21 sent from the registration roller pair 44 into close contact with the belt 26. The belt 26 is provided with, for example, a plurality of circular suction holes in addition to the detection holes 39 described above. The positions and diameters of these suction holes are provided according to the type of the recording medium 21 in order to attract and hold the various recording media 21 on the belt 26. A fan 48 is provided below the platen 22 of the transport mechanism 20. Accordingly, when the fan 48 is driven, air is sucked through the detection holes 39 and the suction holes of the belt 26. At this time, the recording medium 21 is sucked and held on the belt 26 by each air suction force in each detection hole 39 and each suction hole. The suction holding of the recording medium 21 on the belt 26 is not limited to air suction, and a known suction method such as electrostatic suction using an electrostatic force may be used.
An encoder 49 is provided on the driven roller 24, for example. The encoder 49 has a function as a transport information generation unit that generates transport information including the transport amount of the recording medium 21 transported by the transport mechanism 20. The encoder 49 outputs a pulse signal having the number of pulses corresponding to the rotation amount of the driven roller 24, for example. The encoder 49 is not limited to the driven roller 24 but may be provided to the driving roller 23.
On the discharge side of the transport mechanism 20, there is a medium discharge mechanism that discharges the recording medium 21 on which image recording has been performed to the outside of the apparatus, and a discharge medium storage unit that stores the recording medium 21 discharged by the medium discharge mechanism. Is provided.
The control unit 50 performs a series of control of image recording operations in the apparatus. FIG. 7 shows a functional block diagram of the control unit 50. A ROM 52, a RAM 53, an output unit 54, an input unit 55, and an input / output unit 56 are connected to the CPU 51. The ROM 52 stores a program for executing a series of control of the image recording operation. The RAM 53 temporarily stores various data including image data when executing a series of control of the image recording operation. The output unit 54 is connected to the medium supply mechanism 40, the transport mechanism 20, and the image recording unit 28. A registration sensor 45, a top edge sensor 46, an encoder 49, and a line sensor 33 are connected to the input unit 55. An operation unit 57, a display unit 58, and a host computer 59 are connected to the input / output unit 56. Among these, the operation unit 57 includes, for example, a keyboard, a mouse, an operation panel, and the like. As the display unit 58, for example, a liquid crystal display or the like is used.
The CPU 51 includes a tip end information generation unit 60, a side end information generation unit 61, and an image recording control unit 62 by executing a program stored in the ROM 52.
The leading edge information generation unit 60 includes the leading edge detection signal when the leading edge of the recording medium 21 output from the top sensor 46 is detected, and the conveyance information including the conveying amount of the recording medium 21 output from the encoder 49, that is, the driven roller 24. A pulse signal having the number of pulses corresponding to the amount of rotation is taken, and the start timing of image recording on the recording medium 21 and the like are generated based on the leading edge detection signal and the conveyance information of the recording medium 21.
The side edge information generation unit 61 takes in the light amount detection signal corresponding to the received light amount output from the line sensor 33 and the conveyance information including the conveyance amount of the recording medium 21 output from the encoder 49, and these light amount detection signals and Based on the conveyance information of the recording medium 21, information on the positions at both ends of the recording medium 21 is generated.
The side edge information generation unit 61 takes in the conveyance information including the conveyance amount of the recording medium 21 output from the encoder 49, and based on this conveyance information, each detection hole 39 is sequentially on the opening 35 by the movement of the belt 26, that is, the light quantity detection signals outputted at the timing of passing through the propagation path of the output line illumination light L ₁ from the line light source 37 from the line sensor 33 as an active.

Specifically, the side edge information generation unit 61 sets the detection synchronization regions P ₁ and P ₂ at the left and right ends of the line sensor 33 as shown in FIG. These detection synchronization areas P ₁ and P ₂ correspond to, for example, 100 pixels at both the left and right ends of the line sensor 33. That is, the line sensor 33 consists of a left line sensor 33a and the right side line sensor 33b, if the entire pixel is 1 to 2500 pixels, one detection sync region _{P 1} is, for example 1 to 100 pixels on the left side line sensor 33a It corresponds to the other synchronization detection region _{P 2} corresponds to, for example, 2401 to 2500 pixels of the right line sensor 33b.

Side edge information generation unit 61, by setting the respective synchronous detection regions P _1, P _2, each light quantity detection signal level corresponding to the respective synchronous detection regions P _1, P ₂ of the light quantity detection signal outputted from the line sensor 33 The light amount detection signal output from the line sensor 33 is validated only during a period in which is equal to or greater than a preset first threshold.
FIG. 9 shows the level of the light amount detection signal output from the line sensor 33. The level of the light amount detection signal output from the line sensor 33 when the line illumination light L ₁ projected from the light projecting unit 34 to the line sensor 33 is shielded by the belt 26 is _expressed as V _BLT , and the line illumination light through the detection hole 39. The level of the light amount detection signal output from the line sensor 33 when receiving L ₁ is V _REF , and the transmitted light (detection light) when the line illumination light L ₁ passes through the recording medium 21 through the detection hole 39 is received. When the detection level of the light amount detection signal output from the line sensor 33 is V _P , the first threshold value for determining each light amount detection signal corresponding to each detection synchronization region P ₁ , P ₂ of the line sensor 33 is set. V _SP
Detection level _{V P} of the light transmitted through the recording medium 21,
V _REF > V _P > V _BLT
Have the relationship
The first threshold value V _SP for determining each light quantity detection signal corresponding to each detection synchronization region P ₁ , P ₂ is:
V _REF > V _SP > V _P
Have the relationship.
The first threshold value V _SP may be set to V _REF × 0.9 in consideration of deterioration of the light projecting unit 34 and the like, and need not be a fixed value.

Accordingly, the side end information generation unit 61, when a third threshold value for determining the detection level V _P when it receives the light transmitted through the recording medium 21 and V _S, the line illumination light L ₁ through the detection hole 39 The light amount detection signal output from the line sensor 33 when the level V _REF of the light amount detection signal output from the line sensor 33 when the light is received becomes _equal to or higher than the third threshold value V _S is validated. Here, the third threshold value V _S is
V _REF > V _S > V _BLT
Set to

The side edge information generation unit 61 sequentially takes in the light amount detection signals from the activated line sensor 33, and discretely obtains position information of at least one side edge of the recording medium 21 from these light amount detection signals, and these position information. Are interpolated to obtain continuous position information of at least one side end of the recording medium 21.
Specifically, the side edge information generation unit 61 performs image recording on the recording medium 21 by ejecting ink of each color of K, C, M, and Y from the inkjet heads 29 to 32 of the image recording unit 28. For example, as shown in FIG. 10, a margin C is provided at the edge portion of the recording medium 21, and image recording is performed in the recording region R in the margin C. Accordingly, the side edge information generation unit 61 sequentially takes in the light quantity detection signals output from the line sensor 33, and the position information f ₁ , f ₂ , f of the edge of at least one side edge of the recording medium 21 from these light quantity detection signals. ₃ ,..., Fn are obtained discretely, and margin information is added to the position information f ₁ , f ₂ , f ₃ ,. ₁ , g ₂ , g ₃ ,..., Gn are obtained. Further, the image recording control section 62, the position information _{g 1, g 2, g 3} , ..., each position by performing the interpolation process on gn information _{g 1, g 2, g 3} , ..., concatenates between gn Continuous position information, that is, continuous position information of one edge of the recording medium 21 is obtained.
As shown in FIG. 11, when the recording medium 21 is conveyed at an angle α with respect to the conveying direction B, for example, the side edge information generation unit 61 determines the recording medium 21 from the light amount detection signal output from the line sensor 33. Each position information f ₁₁ , f ₁₂ , f ₁₃ ,..., Fm of the inclined edge on one side is obtained discretely, and the position information f ₁₁ , f ₁₂ , f ₁₃ ,. The position information g ₁₁ , g ₁₂ , g ₁₃ ,..., Gm and the inclination angle α of the recording medium 21 are obtained at one side end of the recording area R that is inclined with the margin added. Further side end information generation unit 61, the position information _{g 11, g 12, g 13} , ..., gm and the position by performing interpolation processing on the basis of the inclination angle α of the recording medium 21 information _{g 11, g} 12, g ₁₃ ,..., Gm are connected to obtain continuous position information, that is, continuous position information of the edge of one side edge of the inclined recording medium 21.
The image recording control unit 62 is configured to output each of the colors K, C, M, and Y ejected from the inkjet heads 29 to 32 of the image recording unit 28 based on continuous position information of one edge of the recording medium 21. The ink ejection position is controlled.

Next, the operation of the apparatus configured as described above will be described with reference to a recording operation flowchart shown in FIG.
When an image recording request is issued from the host computer 59 to the CPU 51, the CPU 51 receives the image recording request in step # 1, and proceeds to step # 2 to start supplying the recording medium 21 to the medium supply mechanism 40. In addition to issuing a command, a drive command is issued to the transport mechanism 20, and the medium presence flag is set to “0” in step # 3.
As a result, the separation mechanism 42 in the medium supply mechanism 40 separates the recording medium 21 loaded at the top from the many recording media 21 stored in the medium storage unit 41, and the pickup roller 43 The recording media 21 separated by the mechanism 42 are picked up one by one and sequentially supplied to the downstream side. Each recording medium 21 supplied to the downstream side one by one passes sequentially below the registration sensor 45 and is sent to the registration roller pair 44.
At this time, the registration sensor 45 detects that each recording medium 21 reaches the registration roller pair 44 and outputs an arrival detection signal. Further, the registration roller pair 44 aligns the leading end of the recording medium 21 to align the recording medium 21 and determines the feeding timing to the downstream transport mechanism 20.

  The recording medium 21 fed by the registration roller pair 44 passes between the top edge sensors 46 and is sent to the transport mechanism 20. At this time, the top edge sensor 46 detects the leading edge of the recording medium 21 supplied to the transport mechanism 20 and outputs a leading edge detection signal. In step # 4, the leading edge information generation unit 60 receives a leading edge detection signal from the top edge sensor 46, and determines that the leading edge sensor 46 has detected the leading edge of the recording medium 21.

  At this time, the side edge information generation unit 61 proceeds to step # 5, starts reading the light amount detection signal corresponding to the received light amount output from the line sensor 33, and also reads the recording medium 21 output from the encoder 49. The counting operation of the conveyance information including the conveyance amount, that is, the pulse signal output from the encoder 49 is started.

  On the other hand, the transport mechanism 20 is driven by the drive motor 27 in response to a drive command from the CPU 51. The driving roller 27 is rotated by driving the driving motor 27, and the belt 26 performs a conveying operation. At the same time, the air is sucked through the detection holes 39 and the suction holes of the belt 26 by driving the fan 48. As a result, the recording medium 21 is sucked and held on the belt 26 and is transported in the transport direction B as the belt 26 moves.

Next, the side edge information generation unit 61 determines whether or not the recording medium 21 exists below the line sensor 33 in step # 6. That is, the side edge information generation unit 61 performs a count operation of the pulse signal output from the encoder 49, and whether or not the count value has reached a set count value corresponding to the distance between the top edge sensor 46 and the line sensor 33. Judgment by.
If the count value of the pulse signal has not reached the set count value as a result of this determination, the side edge information generation unit 61 determines that the recording medium 21 has not reached below the line sensor 33, and step # 7 Then, it is determined whether or not the medium presence flag is “1”. At this time, since the medium presence flag is “0”, the side edge information generation unit 61 returns to Step # 6 and waits for the recording medium 21 to reach below the line sensor 33.

When the recording medium 21 reaches below the line sensor 33, the side edge information generation unit 61 moves to step # 8, sets the medium presence flag to “1”, and in the next step # 9, It is determined whether or not the level of the light amount detection signal in the detection synchronization areas P ₁ and P ₂ is equal to or higher than the third threshold value V _S.
That is, the belt 26 of the transport mechanism 20 performs a transport operation by driving the drive motor 27. Due to the movement of the belt 26, the detection holes 39 provided in the belt 26 sequentially pass over the openings 35 provided in the platen 22. On the other hand, the line illumination light L ₁ output from the line light source 37 is reflected by the reflection surface 38 at an angle θ (= 45 °) and emitted from the opening 35.

The line sensor 33, if not passing the detection hole 39 provided in the belt 26 is an opening 35 above, no lighting state line illumination light L ₁ does not detect a is shielded line illumination light L ₁ by the belt 26 Thus, a light amount detection signal of level V _BLT as shown in FIG. 9 is output.

On the other hand, if during the passage the detection hole 39 provided in the belt 26 is an opening 35 above, since the line illumination light L ₁ is incident on the line sensor 33 through the detection hole 39, the line sensor 33, A level V _REF light quantity detection signal is output. The relationship between the levels V _BLT and V _REF of these light quantity detection signals is V _REF > V _BLT . Note that the level V _REF is a state where there is no light blocking object for the line illumination light L ₁ , and thus is the maximum level value of the light amount detection signal output from the line sensor 33, and the level V _BLT is the line illumination light L _1. Since the light is shielded by the belt 26, the minimum level value of the light amount detection signal output from the line sensor 33 is obtained.

When this recording medium 21 on the belt 26 with respect is held by suction, when the detection hole 39 of the belt 26 is passing through the opening 35 above the line illumination light L ₁ is transmitted through the recording medium 21 Is incident on the line sensor 33. At this time the line sensor 33 outputs a light quantity detection signal of the detection level V _P transmitted light from the recording medium 21 (detection light) is received. This detection level V _P has a level relationship of V _REF > V _P > V _BLT .

Accordingly, the side end information generation unit 61, a recording medium when the third threshold value for determining the detection level V _P of the transmitted light 21 when received was V _S, the line illumination light L ₁ through the detection hole 39 Detection of the light quantity output from the line sensor 33 when the respective light quantity detection signal levels V _REF corresponding to the detection synchronization areas P ₁ and P ₂ of the line sensor 33 when receiving the light becomes _equal to or higher than the third threshold value V _S. Enable the signal and disable the others.

  On the other hand, the distance F between the top edge sensor 46 and the line sensor 33 is known, for example, as shown in FIG. 13 by being measured by a design value or an assembly adjustment process of the image recording apparatus. As a result, it is possible to recognize which part of the recording medium 21 is detected by the line sensor 33 based on the count value of the pulse signal output from the encoder 49.

  Therefore, since the side edge information generation unit 61 can determine that the recording medium 21 has not reached the lower side of the line sensor 33 as described above, the light amount detection signal output from the line sensor 33 is invalidated at this time as well. .

Explaining together with the conveyance of the recording medium 21, when the detection hole 39 n-1 reaches below the line sensor 33 as shown in FIG. 13, the detection synchronization areas P ₁ and P ₂ of the line sensor 33 are lined through the detection hole 39. since it receives illumination light _{L 1,} and outputs each light quantity detection signal of the third threshold value _{V S} or higher _{V REF.} However, at this time, since the side edge information generation unit 61 determines that the recording medium 21 has not reached the lower side of the line sensor 33, the light amount detection signal output from the line sensor 33 is invalidated.

Next, when the detection hole 39n reaches the lower side of the line sensor 33 as shown in FIG. 14, each of the detection synchronization regions P ₁ and P ₂ of the line sensor 33 passes through the detection hole 39 and the line illumination light L ₁ as described above. Therefore, each light amount detection signal having a level V _{REF equal to} or higher than the third threshold value V _S is output. At this time, since the side edge information generation unit 61 can determine that the recording medium 21 has reached the lower side of the line sensor 33, the light amount detection signal output from the line sensor 33 is validated.

At this time, the line sensor 33, the line illumination light L ₁ having passed through the detection hole 39n is irradiated onto the recording medium 21, the light amount of the detection level V _P by detecting the transmitted light (detection light) from the recording medium 21 A detection signal is output. Thus, the transmitted light from the recording medium 21 incident on the line sensor 33 does not depend on the surface state of the belt 26.

  As a result, the transmitted light (detection light) from the recording medium 21 detected by the line sensor 33 is not affected by the contamination of the belt 26, adhered foreign matter, and the color of the recording medium 21 is the color of the belt 26. Is not affected by the color. Therefore, the side edge information generation unit 61 can reliably detect the recording medium 21 without erroneously detecting the surface of the belt 26 as the recording medium 21.

However, when the side edge information generation unit 61 validates the light amount detection signal output from the line sensor 33, the light amount detection signal corresponding to the received light amount output from the line sensor 33 and the encoder 49 in step # 10. And the conveyance information including the conveyance amount of the recording medium 21 output from the recording medium 21, information on both end positions of the recording medium 21 is generated based on the light amount detection signal and the conveyance information of the recording medium 21, and the recording medium 21. The CPU 51 is notified of information on the positions of both side edges. For example, if the light quantity detection signal level of the line sensor 33 is as shown in FIG. 9, G ₁ and G ₂ are the end positions on both sides of the recording medium 21, and these end positions G ₁ and G ₂ are at the level V. obtained from the number of pixels the line sensor 33 corresponding to each point of change of the detection level V _P when received _REF and transmitted light of the recording medium 21 (detection light). For example, the side end positions G ₁ and G ₂ of the recording medium 21 are obtained with an accuracy of 0.1 mm or less.
Further, the side edge information generation unit 61 notifies the CPU 51 of information on the position of the tip of the recording medium 21 together with the information on the positions of both ends of the recording medium 21. That is, as shown in FIGS. 13 and 14, the leading end position of the recording medium 21 is F (mm) between the top edge sensor 46 and the line sensor 33, the resolution of the encoder 49 is, for example, 300 dpi, and the top edge sensor 46. The pulse count value of the encoder 49 from when the recording medium 21 is detected until the level of each light quantity detection signal from each detection synchronization area P ₁ , P _{2 of the} line sensor 33 becomes equal to or higher than the third threshold value V _S Then, the distance Q between the tip position of the recording medium 21 and the detection hole 39n is
Q = {(K− (F × 300 / 25.4)} × 25.4 / 300 (4)
Is required.
Hereinafter, each time the detection holes 39n + 1 and 39n + 1 sequentially pass under the line sensor 33, the side edge information generation unit 61 performs information on both side edge positions of the recording medium 21 and information on the position of the leading edge of the recording medium 21. Is notified to the CPU 51.

Next, the side edge information generation unit 61 returns to step # 6 again, determines whether or not the recording medium 21 exists below the line sensor 33, and if not, moves to step # 7 and moves to the medium. It is determined whether or not the presence flag is “1”. At this time, since the medium presence flag is set to “1” in step # 8, it is determined that the recording medium 21 has passed below the line sensor 33, and the process proceeds to step # 11 to set the medium presence flag to “0”. And interpolation processing is performed in the next step # 12.
That is, the side edge information generation unit 61 sequentially takes in the light amount detection signals output from the line sensor 33 as shown in FIG. 10, for example, and each position information of the edge of at least one side edge of the recording medium 21 from these light amount detection signals. f ₁ , f ₂ , f ₃ ,..., fn are obtained discretely.
Next, the side edge information generating unit 61 adds the margin C to each position information f ₁ , f ₂ , f ₃ ,..., Fn to obtain each position information g ₁ on one side edge of the recording area R, g ₂ , g ₃ ,..., gn are obtained.
Next, the image recording control section 62, the position information _{g 1, g 2, g 3} , ..., each position by performing the interpolation process on gn information _{g 1, g 2, g 3} , ..., between gn The continuous position information obtained by joining, that is, the continuous position information of one edge of the recording medium 21 is obtained.
When the recording medium 21 is conveyed at an angle α with respect to the conveying direction B, for example, the side edge information generation unit 61 detects the recording medium 21 from the light amount detection signal output from the line sensor 33 as shown in FIG. Each position information f ₁₁ , f ₁₂ , f ₁₃ ,..., Fm of the inclined edge on one side is obtained discretely.
Next, the side edge information generation unit 61 adds each margin information to each position information f ₁₁ , f ₁₂ , f ₁₃ ,. ₁₁ , g ₁₂ , g ₁₃ ,..., Gm and the inclination angle α of the recording medium 21, and interpolation processing is performed based on the position information g ₁₁ , g ₁₂ , g ₁₃ ,. To obtain continuous position information by connecting the pieces of position information g ₁₁ , g ₁₂ , g ₁₃ ,..., Gm, that is, continuous position information of one edge of the inclined recording medium 21.
Note that the side edge information generation unit 61 discretely stores each piece of position information f ₁ , f ₂ , f ₃ ,..., Fn, etc. of one edge of the recording medium 21 as shown in FIGS. However, the position information of each edge at both ends of the recording medium 21 may be obtained. If the edge positions at both ends of the recording medium 21 are obtained, it is possible to improve the accuracy of obtaining continuous position information of one edge at the recording medium 21.
Next, in step # 13, the image recording control unit 62 is ejected from each of the inkjet heads 29 to 32 of the image recording unit 28 based on the continuous position information of the edge at one side end of the recording medium 21. , M, and Y for controlling the ejection positions of the respective inks.

As described above, according to the first embodiment, the timing at which the detection hole 39 of the belt 26 of the transport mechanism 20 passes over the opening 36 that emits the line illumination light L <b> ₁ projected from the light projecting unit 34. Thus, the light quantity detection signal output from the line sensor 33 that has detected the transmitted light (detection light) of the recording medium 21 is validated, and the edge of one side edge of the recording medium 21 continues based on this valid light quantity detection signal. The obtained position information is obtained, and the ejection positions of the respective inks of K, C, M, and Y ejected from the inkjet heads 29 to 32 of the image recording unit 28 are controlled based on the position information.
Thereby, the transmitted light (detection light) from the recording medium 21 incident on the line sensor 33 passes through the detection hole 39 of the belt 26 and therefore does not depend on the surface state of the belt 26. As a result, the transmitted light (detection light) from the recording medium 21 detected by the line sensor 33 is not affected by dirt on the belt 26, attached foreign matter, etc., and the color of the recording medium 21 becomes the color of the belt 26. Even if they are approximate, they are not affected by the color.
Therefore, the side edge information generation unit 61 can reliably obtain continuous position information of the edge of one side edge of the recording medium 21 without erroneously detecting the surface of the belt 26 as the recording medium 21. However, the image recording position with respect to the recording medium 21 can be controlled with high accuracy from the continuous position information of one edge of the recording medium 21.

The timing at which the light amount detection signal output from the line sensor 33 is validated is that the light amount detection signal levels corresponding to the detection synchronization regions P ₁ and P ₂ among the light amount detection signals output from the line sensor 33 are the first. Since it is set when the threshold value is exceeded, the detection hole 39 of the belt 26 actually reaches below the line sensor 33. Therefore, the line sensor 33 can reliably detect the transmitted light (detection light) of the recording medium 21 even if the moving speed of the belt 26 is changed or set.

Further, even if the recording medium 21 is inclined with respect to the conveyance direction B, an image can be recorded with high accuracy on the recording medium 21 in the margin portion C in consideration of this inclination.
Further, the side edge information generation unit 61 continues the edge of one side edge of the recording medium 21 based on the position information f ₁ , f ₂ , f ₃ ,... Fn of the edge of at least one side edge of the recording medium 21. For example, when a part of the recording medium 21 is conveyed with a bent portion 21a as shown in FIG. 19, the recording medium is determined from the position information of one edge of the recording medium 21. The presence of a bent portion 21a can be detected. When the bent portion 21a of the recording medium 21 is detected, it is possible to notify the CPU 51 of the fact and notify the presence of the bending of the recording medium 21.

Next, a second embodiment of the present invention will be described with reference to the drawings. The same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
15 and 16 show the configuration of the opening 70 provided in the platen 22 of the transport mechanism 20. Reflecting portions 71 and 72 that totally reflect light are provided at the left and right ends of the opening 70, respectively. These reflection parts 71 and 72 are each formed in each mirror surface. Further, a non-reflecting portion 73 that does not reflect light is provided between the reflecting portions 71 and 72. The non-reflective portion 73 has a light guide hole 74 provided in the platen 22 as shown in FIG. The light guide hole 74 is formed so as to be directed downward in the vertical direction with respect to the surface of the platen 22 and bent at an angle of 90 °, for example. At the bent portion of the light guide hole 74, a reflective surface 75 made of a flat mirror surface is provided. The reflecting surface 75 is provided to be inclined by an angle θ (= 45 °) with respect to the optical axis of the line illumination light L ₂ output from the line sensor 76. For example, a light absorbing member may be provided on the back wall of the light guide hole 74. Further, an antireflection agent such as a sponge may be embedded in the non-reflective portion 73.

The line sensor 76 has a built-in light projecting portion for outputting the line illumination light L _2. The line sensor 76 detects the reflected light (detection light) from the reflection light (detection light) or a belt 26 from the recording medium 21 when the line illumination light L ₂ and projected, corresponding to the amount of reflected light Output a light intensity detection signal. The line sensor 76 has a line length longer than the maximum medium width W _MAX of the recording medium 21. For example, as shown in FIG. 18, the line sensor 76 includes a left line sensor 76a and a right line sensor 76b that are connected in a single line to ensure a line length longer than the maximum medium width W _MAX of the recording medium 21. is doing. If the line sensor 75 has a line length longer than the maximum medium width W _MAX of the recording medium 21, one line sensor 76 may be used.

For example, as shown in FIG. 18, the side edge information generation unit 61 sets the detection synchronization regions P ₁₀ and P ₁₁ at the left and right ends of the line sensor 76, respectively, and each of the light amount detection signals output from the line sensor 76. Each time the light quantity detection signal level corresponding to the detection synchronization areas P ₁₀ and P ₁₁ becomes equal to or higher than the second threshold value, the light quantity detection signal output from the line sensor 76 is validated.
Specifically, as shown in FIG. 18, the level of the light amount detection signal output from the line sensor 76 when each of the reflecting portions 71 and 72 is shielded by the belt 26 is set to V _BLT , and each reflecting portion 71, The level of the light amount detection signal output from the line sensor 76 when the reflected light from 72 is received is V _ALL , and the light amount detection signal output from the line sensor 76 when the non-reflecting portion 73 is detected through the detection hole 39. The level is V _L , the detection level of the light amount detection signal output from the line sensor 76 when the reflected light (detection light) from the recording medium 21 is received is V _P1 , and each detection synchronization region P ₁₀ , P of the line sensor 76 is detected. the second threshold value V _S1 for determining the amount of light detection signal corresponding to the _11, the detection level V _P when it receives the reflected light (detection light) from the recording medium 21 When V _SP1 the fourth threshold value for determining,
The detection signal level V _BLT is
V _ALL > V _BLT > V _L
Have the relationship
The second threshold value V _S1 is
V _ALL > V _S1 > V _BLT
Have the relationship
The fourth threshold value V _SP1 is
V _P1 > V _SP1 > V _L
Have the relationship.

The side edge information generation unit 61 sets the level V _ALL of the light amount detection signal output from the line sensor 76 when the reflected light from each of the reflection units 71 and 72 is received through the detection hole 39 to the second threshold value V _S1 or more. When this happens, the light amount detection signal output from the line sensor 76 is validated.

Next, the operation of the apparatus configured as described above will be described.
In the transport mechanism 20, the driving roller 23 is rotated by driving of the drive motor 27, whereby the belt 26 performs the transport operation. At the same time, the air is sucked through the detection holes 39 and the suction holes of the belt 26 by driving the fan 48. As a result, the recording medium 21 is sucked and held on the belt 26 and is transported in the transport direction B as the belt 26 moves.

As the belt 26 moves, the detection holes 39 sequentially pass below the line sensor 76. At this time, the line sensor 76 outputs the line illumination light L ₂ from the light projecting unit with a built. Thereby, the line sensor 76 detects the reflected light (detection light) from the surface of the belt 26 during the period when the detection hole 39 of the belt 26 does not pass below the line sensor 76. Further, the line sensor 76 detects the non-reflective portion 73 through the detection hole 39 during a period in which the detection hole 39 of the belt 26 passes below the line sensor 76.

Here, the sensor of 2500 pixels is used for the line sensor 76 as in the first embodiment. The side edge information generating unit 61, left and example 1 to 100 pixels of the left edge of the line sensor 76a, the right end portion of the example 2401-2500 pixel and each detected synchronization area _{P 10,} respectively, in the right line sensor 76 b, It is set to P _11.

The level V _ALL of the light amount detection signal output from the line sensor 76 when the reflected light from the reflecting portions 71 and 72 is received through the detection hole 39 and the line sensor when the non-reflecting portion 73 is detected through the detection hole 39. The level V _L of the light amount detection signal output from 76 has a relationship of V _ALL > V _L. The level V _BLT of the light amount detection signal output from the line sensor 76 when the line sensor 76 is shielded from light by the belt 26 has a relationship of V _ALL > V _BLT > V _L. The second threshold value V _S1 for determining each light quantity detection signal corresponding to each detection synchronization region P ₁₀ , P ₁₁ of the line sensor 76 is set to a relationship of V _ALL > V _S1 > V _BLT . Also, _{V SP1} the fourth threshold value for determining the detection level _{V P1} when it receives the reflected light from the recording medium 21 (detection light) _is set to satisfy the relationship of _{V P1>} V _SP1> V _L .

However, the side edge information generation unit 61 determines that the level V _ALL of the light amount detection signal output from the line sensor 76 when the reflected light from each of the reflection units 71 and 72 is received through the detection hole 39 is the second threshold value V _S1. The light amount detection signal output from the line sensor 76 is validated when it becomes above, and the others are invalidated.
At this time, the line sensor 76 receives the reflected light (detection light) from the recording medium 21 when the detection hole 39 reaches the lower side, so that the reflected light (detection light) from the recording medium 21 incident on the line sensor 76 is received. ) Does not depend on the surface state of the belt 26. As a result, the reflected light (detection light) from the recording medium 21 detected by the line sensor 76 is not affected by the contamination of the belt 26, adhered foreign matter, and the color of the recording medium 21 is the color of the belt 26. Is not affected by the color. Therefore, the side edge information generation unit 61 can reliably detect the recording medium 21 without erroneously detecting the surface of the belt 26 as the recording medium 21.

When the side edge information generation unit 61 validates the light quantity detection signal output from the line sensor 76, the light quantity detection signal corresponding to the received light quantity output from the line sensor 76 and the recording medium output from the encoder 49. Information on the both end positions of the recording medium 21 is generated based on the light quantity detection signal and the transport information of the recording medium 21, and the information on the both end positions of the recording medium 21 is acquired. Is sent to the CPU 51. For example, if the light quantity detection signal level of the line sensor 76 is as shown in FIG. 18, G ₁₀ and G ₁₁ are both end positions of the recording medium 21, and these both end positions G ₁ and G ₂ are level V. _It is obtained from the number of pixels of the line sensor 76 corresponding to each change point of _L and the detection level _VP1 when the reflected light from the recording medium 21 is received (detection light).
Hereinafter, each time the detection holes 39n + 1 and 39n + 1 sequentially pass below the line sensor 76, the side edge information generation unit 61 performs information on both side edge positions of the recording medium 21 and information on the position of the leading edge of the recording medium 21. Is notified to the CPU 51.
Thereafter, as in the first embodiment, the side edge information generation unit 61 performs an interpolation process to obtain continuous position information of the edge at one side edge of the recording medium 21. Next, the image recording control unit 62 includes K, C, M, and Y ejected from each of the inkjet heads 29 to 32 of the image recording unit 28 based on continuous positional information of one edge of the recording medium 21. The ejection position of each ink of each color is controlled.

As described above, according to the second embodiment, the reflected light (detection light) from the recording medium 21 is detected at the timing when the detection hole 39 of the belt 26 of the transport mechanism 20 reaches below the line sensor 76. The light quantity detection signal output from the line sensor 76 is validated, continuous position information of the edge of one side edge of the recording medium 21 is obtained based on the validated light quantity detection signal, and the image recording unit is based on the positional information. Since the ejection positions of the inks of the respective colors K, C, M, and Y ejected from the 28 inkjet heads 29 to 32 are controlled, it goes without saying that the same effects as those of the first embodiment can be obtained.
If the recording medium 21 is black that hardly reflects light, the line sensor when the non-reflecting portion 73 is detected through the detection level _VP1 and the detection hole 39 when the reflected light (detection light) from the recording medium 21 is received. The level of the light amount detection signal output from 76 is V _L , V _P1 ≈V _L , and it becomes difficult to set V _SP1 as the fourth threshold for detecting the recording medium 21. However, for example, when an image is recorded on the recording medium 21 by an ink jet printer as an image recording apparatus, the black recording medium 21 is hardly recorded. In many cases, the image recording area is formed with a white outline (that is, a black edge). In the case of such a black recording medium 21, the fourth threshold value for detecting the recording medium 21 can be dealt with by changing V _SP1 to a level for detecting a white area in the black recording medium 21. It is.

Further, since the line sensor 76 has a built-in light projecting unit, it is not necessary to provide a separate light projecting unit, and the cost can be reduced accordingly.
In addition, this invention is not limited to said each embodiment, You may deform | transform as follows.
For example, each detection hole 39 provided in the belt 26 is not limited to a rectangular shape, and its shape and dimensions can be arbitrarily changed. Further, the interval between the detection holes 39 is not limited to a fixed interval, and may be provided for each different interval. For example, when the interval between the detection holes 39 is narrowed, for example, as shown in FIG. 10, the position information f ₁ , f ₂ , f ₃ ,. Since the interval can be reduced, the continuous position information of the edge at one side end of the recording medium 21 can be obtained with high accuracy.

1 is an external configuration diagram illustrating a first embodiment of an image recording apparatus according to the present invention. The perspective view which shows the structure of the platen of the conveyance mechanism in the apparatus. The top view which shows the structure of the platen in the apparatus. FIG. 3 is a layout diagram of a line sensor and a platen in the apparatus. The figure which shows the relationship of the magnitude | size of each hole provided in the belt in the apparatus, and a recording medium. The block diagram of the conveyance system in the apparatus. The functional block diagram of the control part in the same apparatus. The schematic diagram which shows each detection synchronous area | region in the right-and-left both ends of the line sensor in the apparatus. The figure which shows the level of the light quantity detection signal output from the line sensor in the apparatus. The figure for demonstrating control of the recording position by the image recording control part in the apparatus. The figure for demonstrating control of the recording position when the recording medium inclines by the image recording control part in the apparatus. 6 is a flowchart of recording operation in the apparatus. The schematic diagram which shows the distance of the registration sensor and line sensor in the apparatus. FIG. 3 is a schematic diagram for obtaining a tip position of a recording medium by the apparatus. The top view of the opening part on the platen which shows 2nd Embodiment of the image recording device which concerns on this invention. The perspective view of the opening part on the platen in the apparatus. The block diagram which shows the light projection part and line sensor in the same apparatus. The figure which shows the level of the light quantity detection signal output from the line sensor in the apparatus. FIG. 3 is a diagram for explaining detection of a bent portion of a recording medium by the apparatus. FIG. 6 is a configuration diagram of a portion related to paper edge detection in a conventional image forming apparatus. 1 is a schematic configuration diagram of a conventional image forming apparatus.

Explanation of symbols

  20: conveying mechanism, 21: recording medium, 22: platen, 23: driving roller, 24: driven roller, 25: tension roller, 26: belt, 27: driving motor, 28: image recording unit, 29 to 32: ink jet Head, 33: Line sensor, 33a: Left line sensor, 33b: Right line sensor, 34: Light projecting part, 35: Opening part, 36: Light guide hole, 37: Line light source, 38: Reflecting surface, 39: Detection hole 40: medium supply mechanism, 41: medium storage unit, 42: separation mechanism, 43: pickup roller, 44: registration roller pair, 45: registration sensor, 46: top edge sensor, 47: suction roller, 48: fan, 49 : Encoder, 50: Control unit, 51: CPU, 52: ROM, 53: RAM, 54: Output unit, 55: Input unit, 56: Input / output unit, 57: Operation 58: display unit, 59: host computer, 60: tip information generation unit, 61: side end information generation unit, 62: image recording control unit, 70: opening, 71, 72: reflection unit, 73: non-reflection unit 74: light guide hole, 75: reflecting surface, 76: line sensor, 76a: left line sensor, 76b: right line sensor.

Claims (22)

A transport mechanism that transports the recording medium by moving a transport member on which the recording medium is placed, a transport information generation unit that generates transport information including the transport amount of the recording medium transported by the transport mechanism, and the transport An image recording apparatus having an image recording unit that records an image on the recording medium conveyed by a mechanism,
A plurality of holes provided in the transport direction of the recording medium with respect to the transport member;
A light-projecting unit that is provided upstream of the image recording unit in the conveyance direction of the recording medium and that irradiates the recording member with the conveyance member and the recording medium that are moving;
A medium detection unit that detects the light emitted from the light projecting unit and detection light based on the light;
A control unit that controls at least the transport mechanism, the image recording unit, and the medium detection unit;
An image recording apparatus comprising: The control unit detects the medium at a timing at which the light emitted from the light projecting unit passes through one of the plurality of holes based on the conveyance information generated by the conveyance information generation unit. A side edge information generation unit that validates the light output from the unit and a detection signal of detection light based on the light and obtains position information of at least one side of the recording medium based on the validated detection signal When,
An image recording control unit that causes the image recording unit to perform image recording on the recording medium based on the position information obtained by the side edge information generation unit;
Comprising at least
The medium detection unit is irradiated from the light projecting unit and passes through one of the plurality of holes, and the medium detection unit is irradiated from the light projecting unit and passes through one of the plurality of holes. The image recording apparatus according to claim 1, wherein at least the detection light transmitted later through the recording medium and the detection light irradiated from the light projecting unit and transmitted through the conveying member are detected. The light projecting unit is provided in an opening of a platen that slidably supports the conveying member below,
The image recording apparatus according to claim 2, wherein the medium detection unit is disposed so as to face the opening.   The side edge information generation unit sets detection synchronization regions at both ends of the medium detection unit, and the detection signal levels corresponding to the detection synchronization regions among the detection signals output from the medium detection unit are first. Whenever the threshold value of 1 or more is reached, the light emitted from the light projecting unit is output from the medium detecting unit when the light passes through one of the plurality of holes and further passes through the recording medium. The image recording apparatus according to claim 2, wherein the detected signal is validated. The side edge information generation unit sets the level of the detection signal output from the medium detection unit when the light emitted from the light projecting unit receives the detection light transmitted through the transport member to V _BLT , The level of the detection signal output from the medium detection unit when the light emitted from the light projecting unit passes through one of the holes and receives the light is V _REF , and is emitted from the light projecting unit. The detection level of the detection signal output from the medium detection unit when the light passes through the one of the plurality of holes and further receives the detection light transmitted through the recording medium is expressed as _VP When the first threshold value for determining the respective detection signals corresponding to the opposite ends of the medium detecting unit and V _SP,
The detection level V _P has a relationship of V _REF > V _P > V _BLT ,
The first threshold value _{V SP} has a relation of _{V REF> V SP> V P} ,
By
5. The image recording apparatus according to claim 4, wherein side end position information of the recording medium is generated based on these relationships. The control unit is configured to output the light output from the medium detection unit at a timing when the light emitted from the light projecting unit passes through the hole based on the transport information generated by the transport information generation unit. A side edge information generation unit that validates a detection signal of detection light based on the light, and obtains position information of at least one side edge of the recording medium based on the valid detection signal;
An image recording control unit that causes the image recording unit to perform image recording on the recording medium based on the position information obtained by the side edge information generation unit;
Comprising at least
The transport mechanism includes a platen having a reflecting portion that reflects the light emitted from the light projecting portion and a non-reflecting portion that does not reflect the light.
The medium detection unit is irradiated from the light projecting unit, passes through one of the plurality of holes, and then reflected by the reflection unit, and is irradiated from the light projecting unit and the recording medium. The image recording apparatus according to claim 1, wherein at least the detection light reflected by the light and the detection light emitted from the light projecting unit and reflected by the conveying member are detected.   The image recording apparatus according to claim 6, wherein each of the reflection units has a mirror surface.   The image recording apparatus according to claim 6, wherein the non-reflective portion includes an anti-reflection member or a reflective member that reflects the light in a direction other than a direction in which the medium detection unit is disposed.   The image recording apparatus according to claim 6, wherein the light projecting unit is arranged in parallel with the medium detection unit. The platen is provided with the reflecting portions at positions corresponding to both ends of the plurality of holes, and the non-reflecting portions are provided between the reflecting portions,
The side edge information generation unit sets detection synchronization regions at both ends of the medium detection unit, and the detection signal levels corresponding to the both ends of the detection signal output from the medium detection unit are second. The light emitted from the light projecting unit that is output from the medium detection unit passes through one of the plurality of holes and is reflected by the recording medium each time the threshold value is greater than or equal to The image recording apparatus according to claim 6, wherein the detection signal in the detection light is validated. The end information generation unit, the detection signal level V _BLT of the light emitted is output from the medium detecting unit when the receiving the detection light reflected by said conveying member from said light projecting portion The level of the detection signal output from the medium detection unit when the light emitted from the light projecting unit passes through one of the holes and is reflected by the reflecting units is expressed as V. _ALL , the level of the detection signal output from the medium detection unit when the light irradiated from the light projecting unit passes through one of the holes and reaches each non-reflecting unit is expressed as V _L , The level of the detection signal output from the medium detection unit when the light emitted from the light unit is reflected by the recording medium and receives the detection light corresponds to V _P1 and the both ends of the medium detection unit To determine each detection signal V _S1 and the second threshold for _the fourth threshold value for determining the detection level V _P1 when receiving the reflected light from the recording medium when the V _SP1,
The detection signal level V _BLT has a relationship of V _ALL > V _BLT > V _L ,
The second threshold value V _S1 has a relationship of V _ALL > V _S1 > V _BLT ,
The fourth threshold value V _SP1 has a relationship of V _P1 > V _SP1 > V _L.
By
The image recording apparatus according to claim 10, wherein side edge information of the recording medium is generated based on these relationships.   The image recording control unit sequentially captures the detection signals validated by the side edge information generation unit, and discretely obtains position information of at least one side edge of the recording medium from the captured detection signals. The image recording apparatus according to claim 2, wherein the position information is obtained by interpolating the position information to obtain continuous position information of at least one side end of the recording medium.   The image recording control unit controls image recording of the image recording unit based on the continuous position information of at least one side end of the recording medium obtained by the interpolation process. The image recording apparatus described.   The image recording apparatus according to claim 1, wherein the plurality of holes are provided at predetermined intervals in the conveyance direction of the recording medium.   2. The image recording apparatus according to claim 1, wherein each of the plurality of holes is formed in a rectangular shape having a longitudinal direction in a direction substantially orthogonal to a conveyance direction of the recording medium.   2. The plurality of holes are formed at intervals shorter than a length of approximately one third of the minimum length with respect to a minimum length in the conveyance direction of the recording medium. Image recording device.   The length of the plurality of holes in the conveyance direction of the recording medium is formed with a length corresponding to the time required for the medium detection unit to detect the light and the detection light during the movement of the conveyance member. The image recording apparatus according to claim 1.   2. The image recording apparatus according to claim 1, wherein each of the plurality of holes is formed with a length equal to or greater than a width of the recording medium in a direction substantially orthogonal to a conveyance direction of the recording medium.   The image recording apparatus according to claim 1, wherein the light projecting unit irradiates linear illumination light in a direction substantially orthogonal to a conveyance direction of the recording medium.   The image recording apparatus according to claim 1, wherein the medium detection unit includes a line sensor.   The image recording apparatus according to claim 1, wherein the medium detection unit has a length equal to or greater than a width of the recording medium. An image recording method for recording an image on the recording medium in a process of placing the recording medium on a conveying member and conveying the recording medium by movement of the conveying member,
It is determined whether or not a plurality of detection holes provided in the transport member have reached a lower part of a medium detection unit that detects the recording medium,
Validate the detection signal output from the medium detection unit when the recording medium is detected at the timing when the detection hole reaches below the medium detection unit,
Based on the valid detection signal, obtain position information of at least one side edge of the recording medium,
Controlling an image recording position on the recording medium based on the position information;
An image recording method.

Images