JP2008272973A - Liquid droplet jet device and image forming apparatus having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid droplet jet device capable of correcting deviation of an ejection region of a liquid droplet occurring due to a difference in a displacement amount between liquid droplet jet heads caused by variation in temperature, and an image forming apparatus having the same. <P>SOLUTION: When an ambient temperature of the liquid droplet jet head is not lower than a prescribed value, a process is advanced to the step 208 that allows an expansion amount acquiring section to acquire an expansion amount of a reference length of each liquid droplet jet head from a first length conversion table correlating an environment temperature around the liquid droplet jet head and the expansion amount of the reference length with each other. In step 300, a printing control section determines that an ejection region of a liquid droplet jet head of which the expansion amount of the reference length is a minimum, is to be a reference region, and then corrects a deviation of an ejection region of any other liquid jet head. Here, the reference length is calculated in consideration of an attachment error of each liquid droplet head. That is, it is possible to eliminate color deviation by correcting the deviation of the ejection region even when the attachment position of each liquid droplet jet head is shifted. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a droplet discharge device that discharges droplets and an image forming apparatus including the droplet discharge device.

  Some image forming apparatuses correct print data according to the expansion and contraction of a recording sheet (hereinafter referred to as a sheet material) due to a change in environmental temperature (Patent Document 1).

  Specifically, the central control unit calculates how much the sheet material expands and contracts from the ambient temperature detected by the temperature sensor, and the magnification adjustment unit corrects the print data in order to adjust the print area accordingly.

This prevents printing by the droplet discharge device provided in the image forming apparatus from sticking out of the sheet material or increasing the image margin of the sheet material.
Japanese Patent Laid-Open No. 3-161378

  Certainly, the sheet material expands and contracts due to a change in environmental temperature and humidity, but similarly, the droplet discharge head provided in the droplet discharge device also deforms due to the temperature change.

  In recent years, in order to support high-speed printing, there is an image forming apparatus in which a long droplet discharge head is fixedly arranged in a direction orthogonal to a sheet material conveyance direction.

  Further, in order to support full color, a plurality of droplet discharge heads are arranged side by side in the sheet material conveyance direction.

  In the case of such a fixed long droplet discharge head, the droplet discharge head of each color is deformed in the longitudinal direction due to a change in the environmental temperature, and the deformation amount is different for each droplet discharge head of each color. The ejection area for ejecting droplets changes for each color. For this reason, a droplet discharge head whose discharge region has become wide discharges useless droplets that do not enter the discharge region of another droplet discharge head.

  In addition, if the deformation position of each droplet discharge head due to a change in environmental temperature is acquired and the displacement of the discharge region is corrected, the mounting position of each droplet discharge head varies depending on the mounting error. It has been difficult to correct the displacement of the ejection region simply by acquiring the deformation amount of each droplet ejection head.

  In view of the above-described facts, the present invention has an object to correct a deviation of a droplet discharge region caused by a difference in deformation amount of each droplet discharge head.

  According to a first aspect of the present invention, there is provided a liquid droplet ejection apparatus comprising: a head unit including a plurality of nozzles that eject liquid droplets; and a liquid droplet ejection head in which the head units are arranged. A discharge reference position for discharging a droplet to a predetermined position of the droplet discharge target was determined for each of the droplet discharge heads while being arranged in parallel and intersecting the transport direction of the droplet discharge target. In the droplet discharge device, a fixed support for fixing one end of the droplet discharge head, and a moving support for supporting the other end of the droplet discharge head so as to be movable in a direction intersecting the transport direction of the droplet discharge target object A length acquisition means for acquiring a reference length of each of the discharge reference position and a fixed position at which the droplet discharge head is fixed to the fixed support; and a direction that intersects the transport direction of the droplet discharge object Of the reference length due to thermal deformation of Elongation acquisition means for acquiring an amount, and another liquid in the reference area with the discharge area of the droplet discharge head having the minimum extension of the reference length acquired by the extension acquisition means as a reference area And print control means for discharging droplets from the nozzles of the droplet discharge head.

  According to the above configuration, the droplet discharge heads for which the discharge reference positions for discharging the droplets to a predetermined position of the droplet discharge target are determined are arranged in parallel. Further, one end of each droplet discharge head is fixed by a fixed support, and the other end is movably supported by a moving support.

  The length acquisition means acquires a reference length between the discharge reference position and a fixed position where each droplet discharge head is fixed to a fixed support.

  When the environmental temperature rises, due to thermal deformation, each droplet discharge head is curved with the other end supported so as to be movable by the moving support based on the fixed position fixed by the fixed support moving in the longitudinal direction. Without changing the length of each droplet discharge head.

  Here, the elongation acquisition means acquires the elongation of the reference length due to thermal deformation.

  Further, the print control means uses the discharge area of the droplet discharge head with the minimum extension of the reference length acquired by the extension acquisition means as a reference area, and nozzles of other droplet discharge heads in this reference area A droplet is discharged from the nozzle.

  In this way, the length acquisition unit acquires the reference length from the discharge reference position to the fixed position for each droplet discharge head, and the elongation amount acquisition unit calculates the extension amount of the reference length due to thermal deformation for each droplet discharge head. The print control means determines the reference area based on the amount of extension of the reference length. For this reason, even when the fixing positions of the respective droplet ejection heads are different due to the mounting error, it is possible to correct the difference in the droplet ejection areas caused by the difference in the deformation amount of each droplet ejection head.

  According to a second aspect of the present invention, there is provided a liquid droplet ejection apparatus according to the first aspect, wherein the nozzle ejects ink, and the print control unit corrects print data in accordance with the reference area to generate another liquid droplet. It is characterized in that the resolution of the discharge head is lowered.

  According to the above configuration, the print control unit corrects the print data in accordance with the reference area to lower the resolution of the other droplet discharge heads.

  That is, the interval between the nozzles of the other droplet discharge heads is wider than that of the discharge region of the droplet discharge head having the minimum extension amount of the reference length acquired by the extension taking means. When droplets are ejected in this state, a deviation occurs in the output image for each droplet ejection head. However, when the printing control means lowers the resolution of the other droplet discharge heads, an image of the same size is formed and printing deviation can be prevented.

  According to a third aspect of the present invention, there is provided a droplet discharge device comprising: a head unit having a plurality of nozzles for discharging droplets; and a droplet discharge head in which the head units are arranged; A discharge reference position for discharging a droplet to a predetermined position of the droplet discharge target was determined for each of the droplet discharge heads while being arranged in parallel and intersecting the transport direction of the droplet discharge target. In the droplet discharge device, a fixed support for fixing one end of the droplet discharge head, and a moving support for supporting the other end of the droplet discharge head so as to be movable in a direction intersecting the transport direction of the droplet discharge target object A length acquisition means for acquiring a reference length between the discharge reference position and a fixed position at which each of the droplet discharge heads is fixed to the fixed support, and a direction that intersects the transport direction of the droplet discharge object Of the reference length due to thermal deformation of An amount-of-elongation acquisition means for acquiring an amount; and a print control means for discharging droplets from the nozzles of the droplet discharge head in the reference area, using the discharge area of the droplet discharge head at room temperature as a reference area. It is characterized by having.

  According to the above configuration, the droplet discharge heads for which the discharge reference positions for discharging the droplets to a predetermined position of the droplet discharge target are determined are arranged in parallel, and one end of each droplet discharge head is further arranged. The fixed support is fixed, and the other end is movably supported by the movable support.

  Further, the length acquisition means acquires each reference length between the discharge reference position and a fixed position where each droplet discharge head is fixed to a fixed support.

  When the environmental temperature rises, due to thermal deformation, each droplet discharge head is curved with the other end supported so as to be movable by the moving support based on the fixed position fixed by the fixed support moving in the longitudinal direction. Without changing the length of each droplet discharge head.

  Here, the elongation acquisition means acquires each elongation of the reference length due to thermal deformation.

  Further, the print control unit discharges droplets from the nozzles of other droplet discharge heads in the reference region, using the discharge region of the droplet discharge head at room temperature as a reference region.

  Thus, the length acquisition unit acquires the reference length from the discharge reference position to the fixed position, and the elongation acquisition unit acquires each extension amount of the reference length due to thermal deformation. Based on this, the print control means discharges the droplets from the nozzles of the other droplet discharge heads, so even if the fixing position of each droplet discharge head is different due to the mounting error, the deformation of each droplet discharge head It is possible to correct the difference in the discharge area of the droplets caused by the difference in amount.

  According to a fourth aspect of the present invention, there is provided the liquid droplet ejection apparatus according to the third aspect, wherein the nozzle ejects ink, and the print control unit corrects print data in accordance with the reference region to correct the droplet. It is characterized in that the resolution of the discharge head is lowered.

  According to the above configuration, the print control unit corrects the print data in accordance with the reference area to lower the resolution of the droplet discharge head.

  In other words, the deformation of each droplet discharge head widens the interval between the nozzles of each droplet discharge head as compared to the discharge region of the droplet discharge head at room temperature. When droplets are ejected in this state, a deviation occurs in the output image for each droplet ejection head. However, when the printing control means lowers the resolution of each droplet discharge head, an image of the same size is formed and printing deviation can be prevented.

  A droplet discharge device according to a fifth aspect of the present invention is the droplet discharge device according to any one of the first to fourth aspects, wherein when the ambient temperature around the droplet discharge head becomes a specified value or more, the elongation acquiring means However, it is characterized in that an elongation amount of the reference length is acquired, and the print control unit discharges droplets from the nozzles in the reference region.

  According to the above configuration, when the environmental temperature around the droplet discharge head is equal to or higher than the specified value, the elongation amount acquisition unit acquires the elongation amount of the reference length, and the print control unit is within the reference region. Droplets are ejected from the nozzle.

  In this way, only when the deformation amount of the droplet discharge head increases, the printing control means controls the nozzles that discharge the droplets, so there is no waste.

  The droplet discharge device according to claim 6 of the present invention is the droplet discharge device according to any one of claims 1 to 4, wherein when the temperature of the droplet discharge head is equal to or higher than a specified value, An elongation amount of a reference length is acquired, and the print control unit discharges droplets from the nozzles in the reference region.

  According to the above configuration, when the temperature of the droplet discharge head becomes equal to or higher than the specified value, the elongation amount acquisition unit acquires the elongation amount of the reference length, and the print control unit removes the liquid from the nozzle in the reference region. Let the drops be ejected.

  In this way, only when the deformation amount of the droplet discharge head increases, the printing control means controls the nozzles that discharge the droplets, so there is no waste.

  The droplet discharge device according to claim 7 of the present invention is the droplet discharge device according to claim 2 or 4, wherein when the number of printed sheets reaches a specified value or more, the extension amount acquisition means acquires the extension amount of the reference length. The print control means discharges droplets from the nozzles in the reference area.

  According to the above configuration, when the number of printed sheets reaches a specified value or more, the stretch amount obtaining unit obtains the stretch amount of the reference length, and the print control unit discharges droplets from the nozzles in the reference region. .

  That is, when the number of printed sheets reaches a specified value, the temperature of the droplet discharge head changes due to the printing operation. In this way, every time the temperature of the droplet discharge head changes, the print control means controls the nozzles that discharge the droplets, so there is no waste.

  According to an eighth aspect of the present invention, in the liquid droplet ejection device according to the second or fourth aspect, for each printing, the elongation amount acquisition unit acquires the elongation amount of the reference length, and the printing control unit A droplet is ejected from the nozzle in the reference region.

  According to the above configuration, the stretch amount acquisition unit acquires the stretch amount of the reference length for each printing, and the print control unit discharges droplets from the nozzles in the reference region.

  As described above, since the elongation amount acquisition unit always acquires the elongation amount of the reference length, the print control unit can control the nozzles that discharge the droplets based on the latest elongation amount of the reference length.

  The droplet discharge device according to a ninth aspect of the present invention is the droplet discharge device according to any one of the first to eighth aspects, wherein the elongation obtaining unit is configured to calculate the ambient temperature around the droplet discharge head and the reference length. Each elongation amount of the reference length is obtained from a first length conversion table that associates the elongation amount with the ambient temperature around the droplet discharge head measured by a temperature sensor.

  According to the above configuration, the elongation amount acquisition unit associates the ambient temperature around the droplet ejection head with the elongation amount of the reference length, and the droplet ejection head measured by the temperature sensor. The amount of elongation of the reference length is obtained according to the ambient temperature of the environment.

  In this way, the elongation acquisition means can easily acquire the elongation using the ambient temperature around the droplet discharge head.

  The droplet discharge device according to a tenth aspect of the present invention is the droplet discharge device according to any one of the first to eighth aspects, wherein the elongation amount acquisition unit includes a temperature of the droplet discharge head and an elongation amount of the reference length. Each of the elongation amounts of the reference length is obtained from the second length conversion table in which the reference length is associated with the temperature of the droplet discharge head measured by the temperature sensor.

  According to the above configuration, the elongation acquisition means includes the second length conversion table that associates the temperature of the droplet discharge head with the extension of the reference length, and the temperature of the droplet discharge head measured by the temperature sensor. , To obtain the elongation amount of the reference length.

  In this way, the elongation acquisition means can easily acquire the elongation using the temperature of the droplet discharge head.

  According to an eleventh aspect of the present invention, in the droplet ejection device according to the second or fourth aspect, the extension amount acquisition unit includes a third length conversion table in which print data and the extension amount of the reference length are associated with each other. The elongation amount of the reference length is acquired by print data generated from image data.

  According to the above configuration, the extension amount acquisition unit includes the third length conversion table that associates the print data with the extension amount of the reference length, and the print data generated from the image data. To get.

  In other words, when the amount of print data is large, the amount of operation of the droplet discharge head is large, so the temperature is expected to rise. When the amount of print data is small, the amount of operation of the droplet discharge head is small, so the temperature does not increase much. Predict. In this way, the elongation acquiring means can easily acquire the elongation without directly measuring the temperature.

  The liquid droplet ejection apparatus according to a twelfth aspect of the present invention is the liquid droplet ejection apparatus according to any one of the first to eighth aspects, wherein the elongation acquisition means is provided at the other end of the liquid droplet ejection head supported by the moving support. An extension amount of the reference length is acquired based on a deformation amount of the droplet discharge head acquired by a detection signal from a first detection unit that detects a position.

  According to the above configuration, the elongation amount acquisition unit is configured to obtain the deformation amount of the droplet discharge head acquired by the detection signal from the first detection unit that detects the position of the other end of the droplet discharge head supported by the moving support. Based on this, the elongation amount of the reference length is acquired.

  In this way, by directly detecting the position of the other end of the droplet discharge head, the stretch amount acquisition means can accurately acquire the stretch amount.

  A droplet discharge device according to a thirteenth aspect of the present invention is the droplet discharge device according to any one of the first to eighth aspects, wherein the elongation acquisition unit is configured to supply droplets discharged from the nozzle onto the droplet discharge target. An extension amount of the reference length is acquired based on a deformation amount of the droplet discharge head acquired by a detection signal from a second detection unit that detects a position.

  According to the above configuration, the stretch amount acquisition unit is configured to obtain the deformation amount of the droplet discharge head acquired by the detection signal from the second detection unit that detects the position of the droplet discharged from the nozzle onto the droplet discharge target. Each elongation amount of the reference length is acquired based on the above.

  If registration detection means for detecting the position of the sheet material is already provided, this is used as a second detector to detect the position of the liquid droplet, and the elongation acquisition means uses each extension amount to detect each extension. The amount can be acquired.

  An image forming apparatus according to a fourteenth aspect of the present invention is provided with the liquid droplet ejection apparatus according to any one of the first to thirteenth aspects.

  According to the above configuration, the image forming apparatus is provided with the droplet discharge device according to any one of claims 1 to 13, so that a print quality is prevented and a high-quality output image is obtained. Can do.

  According to the image forming apparatus of the present invention, it is possible to correct a deviation of a droplet discharge area caused by a difference in deformation amount of each droplet discharge head.

  An embodiment of an image forming apparatus in which a droplet discharge device according to a first embodiment of the present invention is employed will be described with reference to FIGS.

  FIG. 9 schematically shows a configuration of an FWA (Full Width Array) type ink jet printer (hereinafter referred to as “image forming apparatus”) 112 which is an image forming apparatus according to the present embodiment.

  A sheet feeding tray 116 is provided in the lower part of the casing 114 of the image forming apparatus 112, and the sheet material P stacked in the sheet feeding tray 116 can be taken out one by one by a pickup roll 118. The taken sheet material P is transported by a plurality of transport rollers 120 constituting a predetermined transport path 122. Hereinafter, the “transport direction” simply refers to the transport direction of the sheet material P, and “upstream” and “downstream” refer to upstream and downstream in the transport direction, respectively.

  Above the paper feed tray 116, an endless transport belt 128 stretched between a drive roll 124 and a driven roll 126 is disposed. A droplet discharge device 130 is disposed above the transport belt 128 and faces the flat portion 128F of the transport belt 128. This opposed region is a discharge region SE in which droplets are discharged from the droplet discharge device 130. The sheet material P transported along the transport path 122 is held by the transport belt 128 and reaches the discharge region SE, and droplets are discharged from the droplet discharge device 130 at a position facing the droplet discharge device 130. The

  Then, by rotating the sheet material P while being held by the conveying belt 128, it is possible to perform image recording by so-called multi-pass by allowing the sheet material P to pass through the discharge region SE a plurality of times. Of course, the sheet material P may be passed through the ejection region SE only once and image recording may be performed in a so-called one pass.

  In the present embodiment, the droplet discharge device 130 is a long object in which an effective recording area is equal to or greater than the width of the sheet material P (the length in the direction orthogonal to the conveyance direction), and is a so-called FWA (Full Width Array). It has become. In the droplet discharge device 130, four droplet discharge heads 132 corresponding to four colors of yellow (Y), magenta (M), cyan (C), and black (K) are arranged in parallel along the transport direction. And a full-color image can be recorded. Note that a method of discharging droplets in each droplet discharge head 132 is not particularly limited, and a known method such as a so-called thermal method or piezoelectric method can be applied.

  Further, the droplet discharge device 130 may be fixed in a direction orthogonal to the transport direction. However, if the droplet discharge device 130 is configured to move as necessary, the resolution is higher in multipass image recording. Images can be recorded.

  A charging roll 136 connected to a power source (not shown) is disposed on the upstream side of the droplet discharge device 130. The charging roll 136 is driven and rotated while sandwiching the conveyance belt 128 and the sheet material P between the charging roll 136 and a pressing position for pressing the sheet material P against the conveyance belt 128 and a separation position separated from the conveyance belt 128. It is possible to move between. In the pressing position, a predetermined potential difference is generated between the grounded driven roll 126 and the sheet material P can be electrostatically attracted to the conveying belt 128 by applying an electric charge to the sheet material P. The power source may be a DC power source or an AC power source as long as the sheet material P can be charged to a predetermined potential.

  Further, a registration roll (not shown) is provided further upstream than the charging roll 136, and the position and conveyance timing of the sheet material P are adjusted before the sheet material P reaches between the conveyance belt 128 and the charging roll 136. Has been.

  A peeling plate 140 is disposed on the downstream side of the droplet discharge device 130, and the sheet material P can be peeled from the transport belt 128.

  The peeled sheet material P is conveyed by a plurality of discharge rollers 142 constituting a discharge path 144 on the downstream side of the peeling plate 140 and discharged to a paper discharge tray 146 provided at the upper part of the housing 114.

  Further, a cleaning roll 148 that sandwiches the conveying belt 128 with the driving roll 124 is disposed below the peeling plate 140, and the surface of the conveying belt 128 is cleaned.

  In addition, a reversing path 152 composed of a plurality of reversing rollers 150 is provided between the paper feed tray 116 and the conveying belt 128, and the conveying belt 128 reverses the sheet material P on which an image is recorded on one side. In this way, image recording on both surfaces of the sheet material P is formed.

  Between the transport belt 128 and the paper discharge tray 146, an ink tank 154 is provided for storing each of the four color inks. The ink in the ink tank 154 is supplied to the droplet discharge device 130 through an ink supply pipe (not shown). As the ink, various known inks such as water-based ink, oil-based ink, and solvent-based ink can be used.

  With the above configuration, as shown in FIG. 9, in the image forming apparatus 112, the sheet material P taken out from the paper feed tray 116 is transported along the transport path 122 by the transport roller 120 and reaches the transport belt 128. Further, the sheet material P is pressed against the conveyance belt 128 by the charging roll 136, and is adsorbed (closely adhered) to the conveyance belt 128 by the applied voltage from the charging roll 136 and held. In this state, the sheet material P passes through the discharge region SE by circulation of the conveying belt, and droplets are discharged from the nozzles provided in the droplet discharge head 132 of the droplet discharge device 130, so that the sheet material P is formed on the sheet material P. An image is recorded. When recording an image in only one pass, the sheet material P is peeled from the transport belt 128 by the peeling plate 140, transported by the discharge roller 142, and discharged to the paper discharge tray 146. On the other hand, when performing image recording by multi-pass, after the sheet material P is circulated and passed through the discharge area SE until the required number of times is reached, the sheet material P is peeled from the transport belt 128 by the peeling plate 140. Then, it is conveyed by the discharge roller 142 and discharged to the discharge tray 146.

  Next, the droplet discharge head will be described.

  As shown in FIG. 8, the droplet discharge head 132 is supported by a rectangular frame 156 fixed to the main body frame.

  The longitudinal direction of the long side 158 of the frame body 156 is disposed in a direction orthogonal to the conveyance direction of the sheet material P, and the frame body 156 is disposed so as to face the flat portion 128F of the conveyance belt 128 (see FIG. 9). ing.

  Further, a block-like fixed support member 164 as a fixed support is attached to the lower surface of one short side 160A of the frame 156, and a block-like as a moving support is attached to the lower surface of the other short side 160B. A slide support member 166 is attached in the same manner as the fixed support member 164. A long member 168 that spans between the fixed support member 164 and the slide support member 166 and constitutes the droplet discharge head 132 is provided on the lower surface side of the fixed support member 164 and the slide support member 166.

  A plurality of head units 178 are attached to the long member 168. Specifically, as shown in FIG. 7, the long member 168 has a plurality of head mounting portions 176 formed along the longitudinal direction, and a plurality of head units 178 are arranged in the head mounting portion 176. It is attached to the shape. Further, the head unit 178 is provided with a plurality of nozzles (not shown) for ejecting droplets based on the print data on the nozzle surface 178A facing the sheet material P.

  Each of the head units 178 does not have the sheet width of the sheet material P as a single unit, but by arranging a plurality of head units 178 in a row in the sheet material width direction, an image recording area larger than the sheet material width can be formed. It has come to be obtained. That is, even if the droplet discharge head 132 does not move along the width direction of the sheet material P, an image can be formed on the entire surface of the sheet material P only by the movement of the sheet material P, so that high productivity can be obtained. .

  Further, one end 168 </ b> A of the droplet discharge head 132 is fixed to the long member 168 by tightening a screw 170 from a screw hole 164 </ b> H provided in the fixed support member 164.

  In contrast, as shown in FIGS. 6A and 6B, a so-called dovetail groove 172 is formed on the lower surface of the slide support member 166 disposed on the other end 168B side of the droplet discharge head 132. Is formed along the longitudinal direction of the long member 168. Further, a protrusion 174 that is slidably engaged with the groove 172 is provided on the upper surface of the other end 168 </ b> B of the long member 168.

  Therefore, as conceptually shown in FIG. 5, by engaging the protrusion 174 with the groove 172 (see FIG. 6), the protrusion 174 can move in the groove 172, and the droplet discharge head 132 is The fixing support member 164 and the droplet discharge head 132 can be expanded and contracted based on the tightening position of a screw 170 that is an attachment point.

  As shown in FIG. 4, in the longitudinal direction of the long member 168 (in the direction of arrow A in FIG. 4), tightening positions (fixed) of the screws 170Y, 170M, 170C, and 170K for fixing the long member 168 are fixed. The position) differs for each droplet discharge head 132 due to an attachment error.

  Therefore, before shipment from the factory, for each droplet discharge head 132, a discharge reference position 182 for discharging droplets to the central portion in the width direction of the sheet material P conveyed in the arrow B direction is determined.

  In addition, the length acquisition unit 84 (see FIG. 9) provided in the droplet discharge device 130 sets the reference length XS from the discharge reference position 182 to the screw 170 for each droplet discharge device 130. Get before shipping.

  Here, an acquisition method in which the length acquisition unit 84 acquires the reference length XSy from the discharge reference position 182Y to the screw 170Y using the droplet discharge head 132Y will be described.

  First, droplets are discharged onto the sheet material P from a nozzle disposed at the discharge reference position 182Y. Next, the droplet discharge head 132Y is heated, and the temperature ΔT1 at which the droplet discharge head 132Y rises when heated is acquired by a temperature sensor (not shown).

  Further, droplets are ejected onto the sheet material P from the nozzles arranged at the ejection reference position 182Y in a state where the droplet ejection head 132Y is raised by ΔT1. The droplets ejected from the nozzle arranged at the ejection reference position 182Y before the heating and the droplets ejected from the nozzle after the heating are ejected to the sheet material P.

  The droplets before and after heating discharged onto the sheet material P are detected by the detection means for registration detection provided in the image forming apparatus 112, and thereby the movement amount ΔXy of the nozzle disposed at the discharge reference position 182Y. Is acquired.

  Then, when the reference length XSy, the temperature ΔT1, the movement amount ΔXy, and the linear expansion coefficient of the droplet discharge head 132Y are α, the length acquisition unit 84 can acquire the reference length XSy. .

XSy × αΔT1 = ΔXy
Ｘ XSy = ΔXy / αΔT1
As described above, before the image forming apparatus 112 is shipped, the length acquisition unit 84 acquires the reference length XS from the discharge reference position 182 to the screw 170 (fixed position).

  When the image forming apparatus 112 is shipped, the environmental temperature surrounding the image forming apparatus 112 changes. When the environmental temperature changes, the nozzle surface 178A of the droplet discharge head 132 is based on the tightening positions (fixed positions) of the screws 170Y, 170M, 170C, and 170K that fix the fixed support member 164 and the long member 168. The liquid droplets ejected from the nozzles change in the longitudinal direction.

  Here, a description will be given of printing misalignment caused by thermal deformation of each color droplet discharge head 132 in the longitudinal direction.

  As shown in FIG. 9, the droplet discharge device 130 includes droplet discharge heads 132Y, 132M, 132C, and 132K corresponding to yellow, magenta, cyan, and black colors. As described above, the longitudinal direction of each droplet discharge head 132 is arranged in a direction orthogonal to the conveying direction of the sheet material P. For each color, the discharge reference position 182 is on the same line in any of the droplet discharge heads 132 in order to prevent image misregistration, and nozzles that differ for each droplet discharge head 132 due to variations in mounting positions. May be assigned.

  As shown in FIG. 4, the tightening position (fixed position) of the screw 170 for attaching each droplet discharge head 132 to the fixed support member 164 is determined in the length direction for each droplet discharge head 132 due to an attachment error (in the direction of arrow A). ) Is different.

  The droplet discharge heads 132 of the respective colors are deformed in the longitudinal direction based on the tightening position (fixed position) of the screw 170 due to the change in the environmental temperature. That is, as shown in FIG. 3, the length of each droplet discharge head 132 in the longitudinal direction is changed from the position indicated by the dotted line to the position indicated by the dotted line at the other end 168B with respect to the tightening position (fixed position) of the screw 170. Deform.

  If the amount of deformation of the length of each color droplet discharge head 132 is different, the positions of the nozzles arranged at the discharge reference positions 182Y, 182M, 182C, and 182K will be shifted between the droplet discharge heads 132 for each color. For this reason, the discharge area of the liquid droplets discharged from the nozzles also changes for each color.

  In this way, there is a difference in the ejection area for each color, and the position of the nozzle is slightly shifted between the colors, thereby causing a printing shift between colors in the output image.

  3 is exaggerated for the sake of easy understanding.

  Therefore, the flow amount shown in FIG. 1 includes an extension amount acquisition unit 86 that acquires the extension amount of the reference length provided in the droplet discharge device 130 and a print control unit 82 (see FIG. 9) that corrects the print data. Correct color misregistration according to

  First, in step 200, the operator issues a print instruction, and the process proceeds to step 202. In step 202, image data is input to an image input unit 90B (see FIG. 9) provided in the recording head control unit 90.

  Next, the process proceeds to step 204, where the print control unit 82 (see FIG. 9) creates print data from the image data, and the process proceeds to step 206.

  In step 206, the elongation acquisition unit 86 determines whether or not the ambient temperature of the droplet discharge head 132 measured by a temperature sensor (not shown) provided in the vicinity of the droplet discharge head 132 is equal to or higher than a specified value. .

  If it is equal to or greater than the specified value, the process proceeds to step 208, where each droplet discharge head 132 is determined from the first length conversion table that associates the ambient temperature around the droplet discharge head 132 with the amount of extension of the reference length XS. The elongation acquisition unit 86 acquires the elongation of the reference length XS.

  Next, in step 300, the print control unit 82 determines the ejection area of the droplet ejection head 132 with the smallest extension amount of the reference length XS as the reference area.

  Next, the process proceeds to step 302, where the print controller 82 corrects the print data. That is, in order to correct the color misregistration by discharging the droplets from the nozzles of the other droplet discharge heads 132 in the reference region, the resolution of the other droplet discharge heads 132 is lowered according to the amount of extension.

  As shown in FIG. 2, for example, when printing the character “mountain”, the reference region “mountain” shown in FIG. 2A and the heat-expanded droplet shown in FIG. The “mountains” of the ejection head 132 are printed while being shifted in the longitudinal direction (E direction). In such a case, the “mountain” in FIG. 2B is corrected to the “mountain” shown in FIG. . In addition, (circle) shown in FIG. 2 represents the nozzle typically.

  When the correction of the print data is completed, the process proceeds to step 304 and printing is started. If the value is not more than the specified value in step 206, the process proceeds to step 304 to start printing.

  As described above, even when the tightening position of the screw 170 (fixed position) for fixing the droplet discharge head 132 and the fixing support member 164 is shifted due to the mounting error, the extension of the reference length XS of each droplet discharge head 132 is increased. By correcting the print data according to the amount, it is possible to correct the displacement of the discharge area and eliminate the color shift.

  It should be noted that the present invention is not limited to such embodiments, and it will be apparent to those skilled in the art that various other embodiments are possible within the scope of the present invention. For example, in the above embodiment, the print data is corrected when the ambient temperature around the droplet discharge head 132 becomes equal to or higher than a specified value, but the temperature of the droplet discharge head 132 is measured using a thermocouple. The print data may be corrected when the temperature of the droplet discharge head 132 becomes equal to or higher than a specified value, or when the number of continuous prints is counted by a counter and the number of printed sheets becomes equal to or higher than the specified value.

  In the above-described embodiment, the reference region is the discharge region of the droplet discharge head 132 with the minimum extension of the reference length XS acquired by the extension acquisition unit 86. However, the discharge of the droplet discharge head 132 at room temperature is used. The region may be a reference region. In this case, it is necessary to input a reference area in advance in the first length conversion table.

  Next, the image forming apparatus 112 according to the second embodiment will be described.

  In addition, about the same member as 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  In this embodiment, the stretch amount acquisition unit 86 uses the second length conversion table in which the temperature of the droplet discharge head 132 and the stretch amount of the reference length XS are associated to each droplet measured by the thermocouple. The elongation amount of the reference length XS of each droplet discharge head 132 is acquired according to the temperature of the discharge head 132.

  As described above, the elongation amount of the reference length XS of each droplet discharge head 132 can be easily obtained using the temperature of the droplet discharge head 132.

  Next, the image forming apparatus 112 according to the third embodiment will be described.

  In addition, about the same member as 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  In this embodiment, the stretch amount acquisition unit 86 uses the third length conversion table that associates the print data with the stretch amount of the reference length XS, and extends the stretch of each reference length XS from the print data for generating an image. Get the quantity.

  That is, when the amount of print data is large, the amount of operation of the droplet discharge head 132 is large, so the temperature is expected to rise. When the amount of print data is small, the amount of operation of the droplet discharge head 132 is small, so Expect no increase. In this way, the extension amount of the reference length XS of each droplet discharge head 132 can be acquired without measuring the temperature.

  Next, an image forming apparatus 112 according to the fourth embodiment will be described.

  In addition, about the same member as 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  In this embodiment, the stretch amount acquisition unit 86 is acquired by a strain signal detected by a strain sensor as a first detector that detects the position of the other end 162B of the droplet discharge head 132 supported by the slide support member 166. Each elongation amount of the reference length XS is acquired based on the deformation amount of each droplet discharge head 132.

  In this way, the amount of movement of the other end 168B is directly detected, and the amount-of-elongation acquisition unit 86 can acquire each amount of elongation of the reference length XS.

  Next, an image forming apparatus 112 according to the fifth embodiment will be described.

  In addition, about the same member as 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  In this embodiment, the stretch amount acquisition unit 86 is based on the deformation amount of the droplet discharge head 132 acquired by the detection signal from the second detector that detects the position of the droplet discharged from the nozzle onto the sheet material P. Thus, each elongation amount of the reference length XS is acquired. In this case, it is possible to use a detection means for detecting registration as the second detector.

FIG. 3 is a flowchart illustrating a print data correction procedure of the image forming apparatus according to the first embodiment of the present invention. (A) It is the schematic diagram which showed the nozzle surface of the reference | standard area | region which concerns on 1st Embodiment of this invention, and the nozzle notionally. (B) It is a schematic diagram in the state which showed the nozzle surface and nozzle which concern on 1st Embodiment of this invention, and was extended by thermal deformation. (C) It is the schematic which showed the nozzle surface and nozzle which concern on 1st Embodiment of this invention, and correct | amended the state extended by thermal deformation. FIG. 3 is a schematic diagram illustrating a droplet discharge head of the image forming apparatus according to the first embodiment of the present invention, and a state in which each head expands and contracts due to a change in environmental temperature. FIG. 2 is a schematic diagram showing a droplet discharge head of the image forming apparatus according to the first embodiment of the present invention, and showing a state in which the attachment position of the droplet discharge head (tightening position of the screw 170) is shifted for each droplet discharge head. It is. 1 is a side view showing a droplet discharge head of an image forming apparatus according to a first embodiment of the present invention. (A) It is the perspective view which showed the slide end of the droplet discharge head which concerns on 1st Embodiment of this invention. (B) It is the disassembled perspective view which showed the slide end of the droplet discharge head which concerns on 1st Embodiment of this invention. 1 is an exploded perspective view showing a droplet discharge head according to a first embodiment of the present invention. 1 is a perspective view showing a droplet discharge head according to a first embodiment of the present invention. 1 is a schematic configuration diagram illustrating an image forming apparatus according to a first embodiment of the present invention.

Explanation of symbols

82 Print Control Unit 84 Length Acquisition Unit 86 Elongation Acquisition Unit 112 Image Forming Device 130 Droplet Discharge Device 132 Droplet Discharge Head 164 Fixed Support Member (Fixed Support)
166 Slide support member (moving support)
178 Head unit 182 Discharge reference position

Claims (14)

A head unit having a plurality of nozzles for discharging liquid droplets, and a liquid droplet discharging head in which the head units are arranged, and the liquid droplet discharging heads are arranged in parallel across the transport direction of the liquid droplet discharge object In the droplet discharge device, the discharge reference position for discharging the droplet to a predetermined position of the droplet discharge target is determined for each droplet discharge head.
A fixed support for fixing one end of the droplet discharge head;
A moving support for supporting the other end of the droplet discharge head so as to be movable in a direction intersecting the transport direction of the droplet discharge target;
Length acquisition means for acquiring each reference length of the discharge reference position and a fixed position at which the droplet discharge head is fixed to the fixed support;
Elongation acquisition means for acquiring the elongation of the reference length due to thermal deformation in a direction intersecting the conveyance direction of the droplet discharge target;
Using the discharge area of the droplet discharge head with the minimum elongation of the reference length acquired by the extension acquisition means as a reference area, droplets are discharged from the nozzles of other droplet discharge heads in the reference area Printing control means for
A droplet discharge apparatus comprising:   2. The droplet discharge apparatus according to claim 1, wherein the nozzle discharges ink, and the print control unit corrects print data in accordance with the reference area to lower the resolution of another droplet discharge head. . A head unit having a plurality of nozzles for discharging liquid droplets, and a liquid droplet discharging head in which the head units are arranged, and the liquid droplet discharging heads are arranged in parallel across the transport direction of the liquid droplet discharge object In the droplet discharge device, the discharge reference position for discharging the droplet to a predetermined position of the droplet discharge target is determined for each droplet discharge head.
A fixed support for fixing one end of the droplet discharge head;
A moving support for supporting the other end of the droplet discharge head so as to be movable in a direction intersecting the transport direction of the droplet discharge target;
A length acquisition means for acquiring a reference length between the discharge reference position and a fixed position at which each droplet discharge head is fixed to the fixed support;
Elongation acquisition means for acquiring the elongation of the reference length due to thermal deformation in a direction intersecting the conveyance direction of the droplet discharge target;
Print control means for discharging droplets from the nozzles of the droplet discharge head in the reference region, using the discharge region of the droplet discharge head at room temperature as a reference region;
A droplet discharge apparatus comprising:   4. The droplet discharge apparatus according to claim 3, wherein the nozzle discharges ink, and the print control unit corrects print data in accordance with the reference area to lower the resolution of the droplet discharge head.   When the ambient temperature around the droplet discharge head is equal to or higher than a specified value, the stretch amount acquisition unit acquires the stretch amount of the reference length, and the print control unit is in the reference region. The droplet discharge device according to claim 1, wherein the droplet is discharged from a nozzle.   When the temperature of the droplet discharge head becomes equal to or higher than a specified value, the stretch amount acquisition unit acquires the stretch amount of the reference length, and the print control unit removes liquid from the nozzles in the reference region. The droplet discharge device according to claim 1, wherein the droplet discharge device is configured to discharge a droplet.   When the number of printed sheets is equal to or greater than a predetermined value, the stretch amount acquisition unit acquires the stretch amount of the reference length, and the print control unit discharges droplets from the nozzles in the reference region. The droplet discharge device according to claim 2 or 4, characterized in that:   3. The stretch amount acquisition unit acquires the extension amount of the reference length for each printing, and the print control unit causes the droplets to be ejected from the nozzles in the reference region. Or the droplet discharge device described in 4.   The elongation acquisition means includes a first length conversion table that associates an ambient temperature around the droplet discharge head with an extension of the reference length, and the periphery of the droplet discharge head measured by a temperature sensor. The liquid droplet ejection apparatus according to claim 1, wherein each elongation amount of the reference length is acquired based on the environmental temperature of the liquid droplets.   The extension amount acquisition means includes a second length conversion table that associates the temperature of the droplet discharge head and the extension amount of the reference length, and the temperature of the droplet discharge head measured by a temperature sensor. The droplet discharge device according to claim 1, wherein each extension amount of the reference length is acquired.   The extension amount acquisition means acquires the extension amount of the reference length from a third length conversion table in which print data and the extension amount of the reference length are associated with each other and print data generated from the image data. The droplet discharge device according to claim 2 or 4,   The stretch amount acquisition means is based on a deformation amount of the droplet discharge head acquired by a detection signal from a first detection means for detecting the position of the other end of the droplet discharge head supported by the moving support. The liquid droplet ejection apparatus according to claim 1, wherein an elongation amount of the reference length is acquired.   The stretch amount acquisition means is based on a deformation amount of the droplet discharge head acquired by a detection signal from a second detection means for detecting a position of a droplet discharged from the nozzle onto the droplet discharge target. The liquid droplet ejection apparatus according to claim 1, wherein an elongation amount of the reference length is acquired.   An image forming apparatus comprising the droplet discharge device according to claim 1.

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