JP5516036B2 - Liquid ejector - Google Patents

Description

  The present invention relates to a liquid ejecting apparatus including a liquid ejecting head that ejects liquid onto a material to be ejected.

Here, the liquid ejecting apparatus refers to an ink jet recording apparatus, a copying machine, a facsimile, or the like that performs recording on a recording paper by ejecting ink from a liquid ejecting head such as a recording head onto an ejected material such as recording paper. The present invention includes not only a liquid ejecting apparatus that ejects or discharges liquid other than ink but also various liquid consuming apparatuses that eject or eject a minute amount of liquid droplets.
The liquid droplet is a state of liquid ejected or ejected from the liquid ejecting apparatus, and includes liquid droplets having a granular shape, a tear shape, and a thread shape.

  The liquid may be any material that can be ejected or discharged from the liquid ejecting apparatus. For example, it may be in a state in which the substance is in a liquid phase, and is granular such as liquid, sol, gel water, other inorganic solvents, organic solvents, solutions, liquid resins, and liquid metals (metal melts). Including the body. Further, not only a liquid as one state of a substance but also a substance in which particles of a functional material made of a solid such as a pigment or metal particles are dissolved, dispersed or mixed in a solvent are included.

  Typical examples of the liquid include ink and liquid crystal. Here, the ink includes various liquid compositions such as gel ink and hot melt ink in addition to general water-based ink and oil-based ink.

  As a specific example of the liquid ejecting apparatus, for example, a liquid containing materials such as an electrode material and a color material used for manufacturing a liquid crystal display, an EL (electroluminescence) display, a surface emitting display, and a color filter in a dispersed or dissolved form. It may be a liquid ejecting apparatus for ejecting a liquid, a liquid ejecting apparatus for ejecting a bio-organic material used for biochip manufacturing, a liquid ejecting apparatus for ejecting a liquid as a sample used as a precision pipette, a textile printing apparatus, a microdispenser, or the like. Furthermore, a transparent resin liquid such as UV curable resin is used to form a liquid injection device that injects lubricating oil pinpoint onto precision machines such as watches and cameras, and micro hemispherical lenses (optical lenses) used in optical communication elements. It may be a liquid ejecting apparatus that ejects onto a substrate, or a liquid ejecting apparatus that ejects an etching solution such as acid or alkali in order to etch the substrate or the like.

  In a liquid ejecting apparatus having a structure in which liquid ejecting is performed while a liquid ejecting head is scanned with respect to a material to be ejected, the liquid ejected from the liquid ejecting head to the material to be ejected is in the ejection direction (perpendicular to the scanning direction of the liquid ejecting head). In the scanning direction of the liquid ejecting head, and land on the ejected material while moving in the scanning direction of the liquid ejecting head at a constant speed. Therefore, the liquid ejected from the liquid ejecting head to the material to be ejected lands at a position shifted in the scanning direction of the liquid ejecting head from the actual ejected position. For this reason, in the liquid ejecting apparatus having the above structure, there is inevitably a deviation between the position where the liquid is ejected from the ejecting nozzle of the liquid ejecting head and the position where the liquid lands on the liquid ejecting surface of the material to be ejected. In general, in the liquid ejecting apparatus having the above-described configuration, the liquid ejecting head ejects liquid from the liquid ejecting head so that the liquid ejected from the liquid ejecting head is landed on a position where the material to be ejected should land. , “Liquid ejection timing”).

The displacement of the liquid landing position as described above includes the distance from the ejection nozzle of the liquid ejection head to the liquid ejection surface of the material to be ejected (hereinafter referred to as “liquid ejection interval”), and the ejection speed of the liquid from the liquid ejection head. The amount of deviation can be specified from the scanning speed of the liquid ejecting head. That is, the correction value for correcting the liquid ejection timing is uniquely determined from these factors.
Strictly speaking, gravity acceleration and air resistance further act on the liquid ejected from the ejection nozzle of the liquid ejection head, but the effects are extremely small, and in many cases, it can be considered negligible.

  Here, the liquid ejection interval can theoretically be determined from the distance between the support surface of the support member that supports the material to be ejected and the head surface of the liquid ejection head (the ejection port of the ejection nozzle) and the thickness of the material to be ejected. is there. However, in reality, for example, a deformation such as warpage or curl occurs in the material to be ejected, so that a part of the material to be ejected may be lifted from the support surface of the support member. When the lift occurs, the liquid ejection interval fluctuates. If the liquid ejecting interval fluctuates, the displacement amount of the liquid landing position with respect to the liquid ejecting surface of the material to be ejected also fluctuates, so that the liquid cannot be landed at the position where it should originally land, and as a result As a result, the liquid ejection accuracy may be reduced.

  As an example of a conventional technique capable of reducing such a decrease in liquid ejection accuracy, a technique for suppressing the lift of the material to be ejected due to deformation of the material to be ejected, such as warping or curling, is known. Specifically, for example, a printer having a structure that imparts a curved posture to a material to be ejected so that a biasing force in a direction in which the material to be ejected is pressed against a support member is known (see, for example, Patent Document 1). For example, a printer having a structure in which a material to be ejected is pressed against a support member with a member having elasticity or the like is known (see, for example, Patent Document 2). In addition, for example, a printer having a structure in which a negative pressure is generated in a number of suction holes formed in a support member and an ejected material is adsorbed on the support surface of the support member by the negative pressure is known (for example, Patent Document 3). reference). As another conventional technique, a printer including a floating detection device that can detect whether or not an injection target material is lifted from a support member is known (see, for example, Patent Document 3).

Japanese Patent Laid-Open No. 2002-19204 Japanese Patent Laid-Open No. 2002-19205 JP 2006-231557 A

  However, there is a limit to the method of suppressing the lift of the material to be injected as in the prior art described above. Depending on the rigidity of the material to be injected, the degree of deformation of the material to be injected, etc. In some cases, it must be allowed. In other words, depending on the characteristics of the material to be ejected, it may be difficult to completely remove the lift. Therefore, the above-described conventional technique allows a certain degree of decrease in the accuracy of liquid ejection due to the lift of the material to be ejected. I have to do it.

  On the other hand, even in a state where the material to be ejected is lifted, if the lift amount can be accurately specified, highly accurate liquid ejection can be realized by adjusting the liquid ejection timing accordingly. Is possible. However, the float detection device disclosed in Patent Document 3 can detect whether or not a certain amount or more of the ejected material has lifted due to its structure, but the lift amount is accurately determined. It is extremely difficult to identify.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a liquid ejecting apparatus capable of performing highly accurate liquid ejecting even in a state where the material to be ejected is lifted with respect to the support member. It is to be realized.

<First Aspect of the Present Invention>
According to a first aspect of the present invention, a support member that supports a material to be ejected in contact with the back surface of the liquid ejecting surface, a liquid ejecting head that ejects liquid onto the liquid ejecting surface of the material to be ejected supported by the support member A mechanism for scanning the liquid ejecting head with respect to a liquid ejecting surface of the ejected material supported by the support member, an ejected material detection device capable of detecting the ejected material supported by the support member, and a control A first optical system that receives reflected light from a liquid ejection surface of the material to be ejected supported by the support member or a back surface thereof, and the first optical system. A second optical system that forms an image of reflected light on the liquid ejection surface or the back surface of the material to be ejected supported by the support member, and a light receiving element that converts the image formed by the second optical system into an electrical signal and outputs the electrical signal And displacing the first optical system in the optical axis direction of the second optical system. Means for adjusting the position of the first optical system so that the image formed by the second optical system is in focus based on an electrical signal output from the light receiving element. And a means for adjusting the timing of ejecting the liquid from the liquid ejecting head to the material to be ejected based on the position of the first optical system in the in-focus state. .

  The state where the material to be ejected is lifted from the support member (the state where the back surface of the liquid ejection surface of the material to be ejected is separated from the support member) and the state where the material is not lifted (the back surface of the liquid ejection surface of the material to be ejected is the support member) The first optical system in which the image formation by the second optical system is in focus because the optical axis length from the liquid ejection surface of the material to be ejected or the back surface thereof to the second optical system is different The position of will be different. In the state where the material to be ejected is lifted from the support member, the optical axis length from the liquid ejection surface or the back surface of the material to be ejected to the second optical system changes according to the amount of the material to be lifted. That is, the position of the first optical system when the image formed by the second optical system is in an in-focus state varies depending on whether or not the material to be ejected is lifted from the support member, and depends on the amount of lift of the material to be ejected. Change. Therefore, the lift amount of the material to be ejected relative to the support member can be accurately specified from the position of the first optical system when the image formed by the second optical system is in a focused state.

  And from the amount of lift of the material to be ejected relative to the support member, the liquid ejection interval in the state where the material to be ejected is lifted can be specified accurately. Therefore, by adjusting the liquid ejection timing based on the specified liquid ejection interval, it is possible to perform highly accurate liquid ejection even when the material to be ejected is lifted from the support member.

  As a result, according to the first aspect of the present invention, there is an effect that it is possible to realize a liquid ejecting apparatus capable of performing highly accurate liquid ejecting even in a state where the material to be ejected is lifted with respect to the support member. can get.

<Second Aspect of the Present Invention>
According to a second aspect of the present invention, in the liquid ejecting apparatus according to the first aspect described above, the first optical system emits incident light in a direction orthogonal to the support surface of the support member. The liquid ejecting apparatus is characterized in that the optical axis direction of the second optical system is a direction parallel to the support surface of the support member.
In addition, the support surface of a support member means the surface which contacts the back surface of the liquid injection surface of a to-be-injected material, and supports a to-be-injected material.

  According to such a feature, when the first optical system is displaced, the first optical system to the second optical system while maintaining the optical axis length from the liquid ejection surface of the material to be ejected or the back surface thereof to the first optical system. The optical axis length up to can be changed. Therefore, the displacement amount of the first optical system based on the state where the ejected material is not lifted from the support member coincides with the lift amount of the ejected material with respect to the support member. That is, according to the second aspect of the present invention, the lift amount of the material to be ejected relative to the support member can be specified very easily from the position of the first optical system.

<Third Aspect of the Present Invention>
According to a third aspect of the present invention, in the liquid ejecting apparatus according to the first aspect or the second aspect described above, a negative pressure generating device that generates a negative pressure in the suction hole formed in the support surface of the support member. And the control device has means for adjusting a negative pressure generated in the suction hole based on the position of the first optical system in the focused state.

  By generating a negative pressure in the suction hole formed in the support surface of the support member, the material to be ejected supported by the support member is adsorbed by the support member, so that the material to be ejected rises with respect to the support member. Can be suppressed. On the other hand, however, the negative pressure causes problems such as an increase in the transport load when the material to be ejected is transported in the scanning direction. Therefore, it is desirable that the negative pressure generated in the suction hole of the support member is set as low as possible within a range in which lifting of the material to be injected can be suppressed.

  According to the third aspect of the present invention, the negative pressure generated in the suction hole of the support member can be adjusted according to the amount of lifting of the material to be ejected relative to the support member. Therefore, it is possible to minimize adverse effects such as an increase in the transport load when the material to be ejected is transported in the scanning direction, for example, while accurately suppressing the material to be lifted from the support member.

The principal part side view of an inkjet printer. 1 is a schematic block diagram of an inkjet printer. FIG. 3 is a side sectional view illustrating the main part of the recording paper detection device. FIG. 3 is a perspective view illustrating a focus adjustment device of a recording paper detection device. FIG. 3 is a side view schematically illustrating the main part of the recording paper detection device. FIG. 3 is a front view schematically illustrating a flight path of ink ejected from a recording head.

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

<Schematic configuration of inkjet printer 1>
A schematic configuration of the inkjet printer 1 will be described with reference to FIGS. 1 and 2.

FIG. 1 is a side view of an essential part of the ink jet printer 1.
The ink jet printer 1 as a “liquid ejecting apparatus” includes a transport driving roller 11, a transport driven roller 12, a recording paper support member 13, a discharge driving roller 14, a discharge driven roller 15, a carriage 16, and a recording head 17.

  The transport driving roller 11 is formed by applying a high friction coating on the outer peripheral surface of the metal shaft, and rotates by receiving the rotational driving force of the PF motor 31 (FIG. 2). The transport driven roller 12 is pivotally supported so as to be driven to rotate in a state of being biased in a direction in contact with the transport drive roller 11. The discharge driving roller 14 rotates by receiving the rotational driving force of the PF motor 31 (FIG. 2). The discharge driven roller 15 is pivotally supported so as to be driven to rotate and is urged in a direction in which the discharge driven roller 15 contacts the discharge drive roller 14.

  The recording paper support member 13 as a “support member” is an area in which ink is ejected from the recording head 17 (hereinafter referred to as “ink ejection area”), and the recording surface of the recording paper P as a “material to be ejected” ( This is a member that supports the recording paper P in contact with the back surface of the liquid ejection surface. The support surface of the recording paper support member 13 (the surface that supports the recording paper P and is in contact with the back surface of the recording paper P; the same applies hereinafter) or the portion where the back surface of the recording paper P faces is provided with a number of suction holes ( (Not shown) is formed. The large number of suction holes generate a negative pressure by operating a suction device 36 disposed at the bottom of the recording paper support member 13. The suction device 36 is controlled by a control device 100 described later.

  The carriage 16 is supported so as to be able to reciprocate in the main scanning direction X by a carriage support frame 19 with which a carriage guide shaft 18 inserted into the bearing portion 161 and a supported portion 162 abut. The main scanning direction X is a direction that intersects the sub-scanning direction Y (the conveyance direction of the recording paper P) along the recording surface of the recording paper P supported by the recording paper support member 13. The carriage guide shaft 18 and the carriage support frame 19 are disposed along the main scanning direction X. The carriage 16 is connected to an endless belt (not shown) that rotates in both directions by the rotational driving force of the CR motor 32 (FIG. 2). The endless belt is hung on a driving pulley and a driven pulley (not shown) of the CR motor 32, and is disposed substantially parallel to the carriage guide shaft 18 and the carriage support frame 19. The carriage 16 can be reciprocated in the main scanning direction X by bidirectionally rotating the endless belt with the driving force of the CR motor 32.

  The recording head 17 as a “liquid ejecting head” is mounted on the carriage 16 so that the head surface faces the recording surface of the recording paper P supported by the recording paper support member 13. The head surface of the recording head 17 is provided with a number of ejection nozzles (not shown) for ejecting ink onto the recording surface of the recording paper P to form dots. Ink is supplied to the recording head 17 from an ink tank (not shown) provided in the main body of the inkjet printer 1 via an ink tube (not shown).

  In the inkjet printer 1 having the above-described configuration, the fed recording paper P is supported by the recording paper support member 13 and ink is ejected from the head surface of the recording head 17 that reciprocates in the main scanning direction X. By repeating the main scanning operation in which dots are formed in the sub-scanning direction and the sub-scanning operation in which the dots are transported in the sub-scanning direction Y by a predetermined transport amount, recording is performed on the recording surface. A series of these recording controls are executed by the control device 100 having a known microcomputer control circuit.

FIG. 2 is a schematic block diagram of the ink jet printer 1.
The control device 100 includes a ROM 101, a RAM 102, an ASIC (Application Specific Integrated Circuit) 103, a CPU (Central Processing Unit) 104, a nonvolatile memory 105, a PF motor driver 106, a CR motor driver 107, a head driver 108, and an MR motor driver 109. It has. The ROM 101, RAM 102, ASIC 103, CPU 104, and nonvolatile memory 105 are connected to the system bus of the control device 100. The PF motor driver 106, the CR motor driver 107, the head driver 108 and the MR motor driver 109 are connected to the ASIC 103.

  The ROM 101 stores a recording control program (firmware) and the like necessary for the control of the ink jet printer 1 by the CPU 104. The RAM 102 is used as a work area for the CPU 104 and a storage area for recording data. The ASIC 103 has a control circuit for performing speed control of a PF motor 31 that is a DC motor, a CR motor 32 and an MR motor 264 described later, and nozzle drive control of the recording head 17. The ASIC 103 sends the control signal of the PF motor 31 to the PF motor driver 106, the control signal of the CR motor 32 to the CR motor driver 107, the control signal of the recording head 17 to the head driver 108, and the control signal of the MR motor 264 to the MR motor. Each is sent to the driver 109. Further, the ASIC 103 has an interface function with the personal computer 200. The CPU 104 performs arithmetic processing for executing recording control of the inkjet printer 1 and other necessary arithmetic processing. The nonvolatile memory 105 stores various data necessary for processing of the recording control program.

  The ink jet printer 1 further includes a linear encoder 33, a rotary encoder 34, a mirror encoder 35, and an image sensor 25. Output signals of the linear encoder 33, the rotary encoder 34, the mirror encoder 35, and the image sensor 25 are input to the CPU 104 via the ASIC 103.

  A known linear encoder 33 is an encoder for detecting the position and moving speed of the carriage 16. When the carriage 16 reciprocates in the main scanning direction X, a pulse signal having a period corresponding to the moving speed moves. The number corresponding to the quantity is output. The known rotary encoder 34 is an encoder for detecting the rotation amount of the transport driving roller 11 and the like, and the rotation of the transport driving roller 11 and the discharge driving roller 14 generates a pulse signal having a period corresponding to the rotational speed. A number corresponding to the amount of rotation is output. The mirror encoder 35 and the image sensor 25 will be described later.

<Configuration of Recording Paper Detection Device 20>
The ink jet printer 1 includes a recording paper detection device 20 as an “ejected material detection device” capable of detecting the recording paper P supported by the recording paper support member 13. Hereinafter, the configuration of the recording paper detection device 20 will be described with reference to FIGS. 3 and 4.

FIG. 3 is a side sectional view illustrating the main part of the recording paper detection device 20. FIG. 4 is a perspective view illustrating the focus adjustment device 26 of the recording paper detection device 20.
The recording paper detection device 20 includes a light emitting element 21, a reflecting mirror 22, a filter 23, a telecentric optical system 24, an image sensor 25, and a focus adjustment device 26.

  The light emitting element 21 is disposed in a mounting recess 133 formed on the inner peripheral surface of the long hole 132 that communicates from the support surface 131 of the recording paper support member 13 to the reflecting mirror 22. The light emitting element 21 irradiates light to a portion located in the long hole 132 on the back surface of the recording paper P supported by the recording paper support member 13. For example, a light bulb or a light emitting diode (LED) can be used as the light emitting element 21.

  The reflecting mirror 22 as the “first optical system” is an optical system that receives reflected light from the back surface of the recording paper P supported by the support surface 131 of the recording paper support member 13 through the long hole 132 of the recording paper support member 13. is there. More specifically, the reflecting mirror 22 is disposed at an angle of 45 degrees with respect to incident light in a direction orthogonal to the support surface 131 of the recording paper support member 13, and the incident light is transmitted to the recording paper support member 13. Reflected in a direction parallel to the support surface 131. In the present embodiment, the “first optical system” may use, for example, a known prism as an optical component in addition to using the reflecting mirror 22.

  The filter 23 is provided to protect the telecentric optical system 24 from, for example, dust or ink mist.

  The telecentric optical system 24 as the “second optical system” causes the image sensor 25 to form an image of the reflected light on the back surface of the recording paper P supported by the support surface 131 of the recording paper support member 13 via the reflecting mirror 22. It is an optical system. The known telecentric optical system 24 is an optical system in which the principal ray is parallel to the lens optical axis, and the light is incident on the image sensor 25 perpendicularly.

  The image sensor 25 as a “light receiving element” converts the image formed by the telecentric optical system 24 into an electrical signal and outputs it to the control device 100 (FIG. 2). The image sensor 25 is, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor, a CCD (Charge Coupled Device) image sensor, or the like.

  In this way, by adopting the recording paper detection device 20 having a structure in which the optical axis from the back surface of the recording paper P to the image sensor 25 is refracted by 90 degrees by the reflecting mirror 22, the possibility that the ink jet printer 1 is increased in size is reduced. Can do.

  The focus adjusting device 26 as a “displacement device” is a device that adjusts the focal point of the telecentric optical system 24 by displacing the reflecting mirror 22 in the optical axis direction of the telecentric optical system 24 (direction indicated by reference symbol A). A portion 261, a slide movable portion 262, a rotary shaft 263, and the MR motor 264.

  The base portion 261 supports the slide movable portion 262 so as to be slidable in the optical axis direction A of the telecentric optical system 24. The slide movable unit 262 is provided with the reflecting mirror 22 at an angle of 45 degrees with respect to the optical axis direction A. In order to detect the position of the reflecting mirror 22, the above-described mirror encoder 35 is provided on the rotating shaft of the MR motor 264 (not shown). The mirror encoder 35 is an encoder having the same structure as the rotary encoder 34. When the MR motor 264 rotates, a pulse signal having a period corresponding to the rotation speed is output in a number corresponding to the rotation amount. .

  The rotating shaft body 263 is pivotally supported by the base portion 261, and rotates when the rotation of the MR motor 264 is transmitted. A male spiral groove is formed on the outer peripheral surface of the rotating shaft body 263. A cylindrical portion (not shown) through which the rotary shaft 263 is inserted is integrally formed at the bottom of the slide movable portion 262, and the male spiral of the rotary shaft 263 is formed on the inner peripheral surface of the cylindrical portion. A female spiral groove in which the groove is screwed is formed. Therefore, by rotating the MR motor 264 bidirectionally, the slide movable unit 262 that supports the reflecting mirror 22 slides in the optical axis direction A of the telecentric optical system 24, thereby adjusting the focal point of the telecentric optical system 24. .

<Ink ejection control by the control device 100>
Ink ejection control by the control device 100 will be described with reference to FIGS. 5 and 6.

  FIG. 5 is a side view schematically showing the main part of the recording paper detection apparatus 20.

  The control device 100 adjusts the slide position of the reflecting mirror 22 based on the electrical signal output from the image sensor 25 so that the image formed by the telecentric optical system 24 is in focus in the image sensor 25. This may be executed, for example, at a predetermined timing (for example, timing of the main scanning operation) before starting recording on the recording paper P or during execution of recording on the recording paper P.

  Here, when the recording paper P is not lifted from the support surface 131 of the recording paper support member 13, the optical axis length from the back surface of the recording paper P to the reflecting mirror 22 is H1, and the image formed by the telecentric optical system 24 is in focus. The optical axis length from the reflecting mirror 22 in the state to the image sensor 25 is L1, and the sliding position of the reflecting mirror 22 at this time is the reference position B (FIG. 5A). The reference position B is specified in advance by experiments or the like, and information regarding the position is stored in the nonvolatile memory 105. In the state where the recording paper P is lifted from the support surface 131 of the recording paper support member 13, the optical axis length from the reflecting mirror 22 to the image sensor 25 where the image formation by the telecentric optical system 24 is in focus is L2. The difference between the sliding position of the reflecting mirror 22 and the reference position B is ΔL (FIG. 5B).

  The optical axis length from the back surface of the recording paper P to the image sensor 25 when the image formed by the telecentric optical system 24 is in focus is such that the recording paper P is not lifted from the support surface 131 of the recording paper support member 13. , H1 + L1 (FIG. 5A). On the other hand, when the recording paper P is lifted from the support surface 131 of the recording paper support member 13, ΔH + H1 + L2 (FIG. 5B). Here, the image formation by the telecentric optical system 24 is in focus in the image sensor 25 when the optical axis length from the back surface of the recording paper P to the image sensor 25 becomes a constant optical axis length. That is, if the image formed by the telecentric optical system 24 is in a focused state, the optical axis length from the back surface of the recording paper P to the image sensor 25 is the same even when the recording paper P is not lifted or lifted. Should be the same length. Therefore, the following equation (1) is established.

H1 + L1 = ΔH + H1 + L2 (1)
Since L2 = L1−ΔL, substituting this into equation (1) and rearranging results in the following equation (2).

ΔH = ΔL (2)
That is, in a state where the recording paper P is lifted from the support surface 131 of the recording paper support member 13, the lift amount ΔH is based on the slide position of the reflecting mirror 22 when the image formed by the telecentric optical system 24 is in focus and the reference. This coincides with the difference ΔL from the position B. That is, the lifting amount ΔH of the recording paper P can be accurately and extremely easily specified from the slide position of the reflecting mirror 22 when the image formed by the telecentric optical system 24 is in a focused state.

  FIG. 6 is a front view schematically illustrating a flight path of ink ejected from the ejection nozzles of the recording head 17 onto the recording paper P.

  When the control device 100 ejects ink from the recording head 17 onto the recording paper P while reciprocating the carriage 16 in the main scanning direction X, the control device 100 actually records the recording paper at the position where the ink is ejected from the ejection nozzles of the recording head 17. There is inevitably a deviation from the position where the ink lands on P. This is because ink is ejected from the recording head 17 while moving the carriage 16 to the stationary recording paper P. In other words, the ink ejected from the ejection nozzles of the recording head 17 moves at a constant speed in the ejection direction at the ejection speed Vm, and at the same time moves on the recording paper P while moving at a constant speed at the movement speed Vcr of the carriage 16 in the movement direction of the carriage 16. Since landing, the landing is made at a position shifted by a distance LX in the moving direction of the carriage 16 from the actually ejected position.

Here, when the distance between the head surface of the recording head 17 and the recording surface of the recording paper P when the recording paper P is not lifted from the support surface 131 of the recording paper support member 13 is PG, the distance LX at that time is: It can be derived from the following equation (3).
Distance LX = Vcr × PG / Vm (3)
The control device 100 ejects ink from the ejection nozzles of the recording head 17 (hereinafter, referred to as “landing position C”) (hereinafter, simply referred to as “position C where the ink is to be landed”). , Referred to as “ink ejection timing”). More specifically, the position at which ink is ejected from the ejection nozzles of the recording head 17 is shifted to the upstream side in the movement direction of the carriage 16 by an amount corresponding to the distance LX. Accordingly, the ink ejected from the ejection nozzles of the recording head 17 can be landed accurately at the position C where the ink should land.
Strictly speaking, although gravity acceleration and air resistance act on the ink ejected from the ejection nozzles of the recording head 17, the influences thereof are extremely small, and in most cases, it can be considered negligible.

  Further, the control device 100 adjusts the ink ejection timing based on the slide position of the reflecting mirror 22 when the image formed by the telecentric optical system 24 is in a focused state. That is, in response to a change in PG caused by the recording paper P being lifted from the support surface 131 of the recording paper support member 13, the control device 100 determines the recording head 17 in accordance with the specified amount of change in PG (lifting amount ΔH). The timing for ejecting ink from the ejection nozzles is adjusted. More specific description will be given below.

PG ′ when the recording paper P is lifted is narrowed by the lifting amount ΔH of the recording paper P with respect to PG when the recording paper P is not lifted. Therefore, the flight distance of the ink ejected from the ejection nozzles of the recording head 17 is shortened by the lift amount ΔH. That is, the distance LX from which the landing position shifts is shorter than the distance LX ′ when the recording paper P is lifted. This distance LX ′ can be derived from the following equation (4).
Distance LX ′ = Vcr × PG ′ / Vm (4)
The control device 100 delays the ink ejection timing by an amount corresponding to the distance difference D between the distance LX when the recording paper P is not lifted and the distance LX ′ when the recording paper P is lifted. As a result, even when the recording paper P is lifted from the support surface 131 of the recording paper support member 13, it is possible to make the ink land at the position C to be landed.

  In this way, according to the present invention, it is possible to perform highly accurate ink ejection even when the recording paper P is lifted from the support surface 131 of the recording paper support member 13.

<Other embodiments and modifications>
The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say.

  For example, in the above embodiment, the suction device 36 can also be controlled based on the slide position of the reflecting mirror 22 when the image formed by the telecentric optical system 24 is in focus. More specifically, for example, when the recording paper P is hardly lifted from the support surface 131 of the recording paper support member 13, that is, when the specified lift amount ΔH is extremely small, the suction device 36 is stopped. On the other hand, in a state where the recording paper P is lifted from the support surface 131 of the recording paper support member 13, the negative pressure generated in the suction hole of the support surface 131 of the recording paper support member 13 is increased or decreased according to the lift amount ΔH. To do. As a result, the suction by the suction device 36 can be minimized, so that the recording paper P is prevented from being lifted from the support surface 131 of the recording paper support member 13 and the conveyance load of the recording paper P is increased to increase the conveyance accuracy. It is possible to minimize the adverse effects caused by the negative pressure generated in the suction hole, such as a decrease in the pressure.

  Further, for example, in the above-described embodiment, based on the electrical signal output from the image sensor 25, the movement amount and movement speed of the recording paper P in the sub-scanning direction Y are detected by, for example, known template matching, etc. The actual transport speed and transport amount of P may be specified, and the rotation control of the transport driving roller 11 may be executed based on the specified transport speed and transport amount. As a result, for example, it is possible to transport the recording paper P with high accuracy by correcting a transport error caused by a slip generated on the contact surface between the transport driving roller 11 and the recording paper P. Accordingly, it is possible to realize the conveyance of the recording paper P with higher accuracy than the case where the conveyance control of the recording paper P is performed based only on the output signal of the rotary encoder 34.

  Further, for example, the image formed on the image sensor 25 via the reflecting mirror 22 and the telecentric optical system 24 may be reflected light from the recording surface of the recording paper P supported by the recording paper support member 13. Furthermore, the “first optical system” is not particularly limited to the reflecting mirror 22, and for example, a lens may be used. In this case, the optical axis from the recording paper P supported by the recording paper support member 13 to the image sensor 25 is a straight line, but even in such an aspect, it is based on the position of the “first optical system” in the focused state. Needless to say, the lifting amount ΔH of the recording paper P can be specified. The “second optical system” is not particularly limited to the telecentric optical system 24, and any optical system that can image the reflected light of the recording surface of the recording paper P or the back surface thereof on the image sensor 25 is used. Such an optical system may be used.

  Further, for example, in the above embodiment, it is more preferable to provide a mechanism capable of removing ink mist and the like adhering to the reflecting mirror 22. More specifically, by providing a mechanism for sliding a removing member made of an elastic material such as rubber against the mirror surface of the reflecting mirror 22, the ink mist adhering to the mirror surface of the reflecting mirror 22 can be wiped off and removed. it can.

DESCRIPTION OF SYMBOLS 1 Inkjet printer, 13 Recording paper support member, 17 Recording head, 20 Recording paper detection apparatus, 21 Light emitting element, 22 Reflective mirror, 23 Filter, 24 Telecentric optical system, 25 Image sensor, 26 Focus adjustment apparatus, 100 Control apparatus, P Recording paper, X main scanning direction, Y sub-scanning direction

Claims (2)

A support member that supports the material to be ejected in contact with the back surface of the liquid ejection surface;
A liquid ejecting head that ejects liquid onto the liquid ejecting surface of the material to be ejected supported by the support member;
A mechanism for scanning the liquid ejecting head with respect to the liquid ejecting surface of the material to be ejected supported by the support member;
An ejected material detection device capable of detecting an ejected material supported by the support member;
A control device,
The ejected material detection device includes a first optical system that receives reflected light from the liquid ejecting surface of the ejected material supported by the support member or the back surface thereof;
A second optical system that forms an image of the reflected light of the liquid ejection surface of the material to be ejected supported by the support member or the back surface thereof via the first optical system;
A light receiving element that converts an image formed by the second optical system into an electric signal and outputs the electric signal;
A displacement device for displacing the first optical system in the optical axis direction of the second optical system,
The control device adjusts the position of the first optical system based on an electrical signal output from the light receiving element so that the image formed by the second optical system is in focus.
Have a, and means for adjusting the timing of ejecting the liquid to the ejection target material from the liquid ejecting head based on the position of the first optical system in the focus state,
The first optical system is an optical system that reflects incident light in a direction perpendicular to the support surface of the support member in a direction parallel to the support surface of the support member, and the optical axis direction of the second optical system is The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is in a direction parallel to a support surface of the support member . The liquid ejecting apparatus according to claim 1 , further comprising a negative pressure generating device that generates a negative pressure in a suction hole formed in a support surface of the support member,
The liquid ejecting apparatus according to claim 1, wherein the control device includes means for adjusting a negative pressure generated in the suction hole based on a position of the first optical system in the focused state.

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