JP5252293B2 - Recording device - Google Patents

Description

  The present invention relates to a recording apparatus, and more particularly to a technique for cleaning a nozzle surface of a recording head.

  A technique for ejecting ink droplets from a recording head is used in various fields such as a printer, a color filter manufacturing apparatus, and a circuit board pattern creating apparatus. In a recording apparatus using such a recording head, in order to perform a recording operation, the recording head is mounted on a carriage with respect to the recording medium, the recording head is moved in the main scanning direction, and recording is performed in the sub-scanning direction orthogonal to the main scanning direction. There are a serial type that includes a medium conveying means and enables a recording operation, and a line type that arranges a recording head with a width equal to the width of the recording medium and performs the recording operation only by conveying the recording medium. In both types, the recording operation is performed by ejecting ink droplets from the nozzles.

  In such a recording apparatus, it is important that the state of the nozzles of the recording head is appropriate in order to obtain a good image quality by stabilizing the ink ejection operation. The state that is not preferable as the state of the nozzle is not a state in which foreign matter such as fixed ink or mist or paper dust of the recording medium is attached in the vicinity of the nozzle, nor is the state in which the ink in the nozzle is thickened or fixed by drying. In order to avoid these undesirable conditions, a general recording apparatus is equipped with a maintenance and recovery device. This maintenance / recovery device is a cleaning operation that removes foreign matter, consisting of an elevating device that contacts the nozzle surface with a cap that seals the nozzle, that is, a capping state, a wiper that wipes off the nozzle surface, and a pump that sucks ink from the nozzle surface. Then, the moisturizing capping operation of the nozzle in the idling state in which the recording operation is not performed is performed. The cleaning operation is completed after the head nozzle surface is capped with a cap and ink is sucked from the nozzle by a communicating pump, and then the capped state is released and the ink and foreign matter adhering to the nozzle surface are wiped with a wiper. The moisturizing capping operation is performed by bringing the cap into contact with the nozzle surface by the lifting device. Here, the capping state of the nozzle and the cap is a very important characteristic for the maintenance and recovery function. The contact state is determined by the relative positional relationship between the nozzle and the cap and the contact pressure between the cap and the nozzle.

  The nozzle and cap capping operation will be described using an example of a serial printer. The carriage abuts against the reference position in the scanning direction at the start of the recording operation, and can know the cap position of the maintenance / recovery device determined based on the abutted position. The head mounted on the carriage can move to a capping position by moving a predetermined amount from the reference position. With the head in the capping position, the cap is lifted by the lifting device, and a contact state is created by the biasing force of a spring or the like. However, in such a recording apparatus, it is not possible to suppress positional deviation when external force such as impact or vibration is applied during capping. In addition, it is impossible to avoid a decrease in contact pressure due to variations in the components themselves and deterioration of the spring over time. Therefore, Patent Document 1 proposes that a pressure sensor is provided in the nozzle of the recording head to monitor the capping state by setting the contact pressure with the cap to a predetermined value.

  By the way, when the recording head ejects ink droplets, ink mist is generated in addition to the main recording main droplets. Mist is generated in association with the main droplets of the discharged droplets and adheres to various places in the apparatus without landing on the recording medium. In particular, the adhesion to the nozzle surface starts to increase in viscosity with the passage of time immediately after the adhesion, and tends to cause defects such as nozzle clogging. In order to solve such a problem, Patent Document 2 proposes to perform a wiping operation for wiping the nozzle surface at regular intervals with a wiper of an elastic member such as rubber in order to avoid defects. The nozzle surface cleaning performance by the wiping operation is determined by the contact pressure when the wiper contacts the nozzle and the relative speed between the nozzle surface and the wiper. The wiping operation will be described in the case of a serial type recording apparatus. The wiper is prevented from protruding from the head nozzle surface so as not to interfere with the nozzle surface during the recording operation. The wiper is arranged in a maintenance / recovery mechanism having a movable structure that protrudes when wiping is performed. The wiping operation is performed by the carriage scanning and moving on the wiper while the wiper is protruding. Here, the protrusion amount of the wiper with respect to the recording head needs to be appropriately controlled to a desired value. However, since it is a movable part, it is very expensive to improve accuracy.

  Even if the recording apparatus is operated accurately, the wiper wear deterioration over time is unavoidable and an error occurs in the protruding amount, and the contact pressure against the recording head nozzle surface also generates an error from an appropriate value. . Further, when such an error occurs, it cannot be determined on the apparatus whether the contact pressure of the wiper is appropriate. Considering the above error, it may be possible to set a large amount of protrusion in advance.

  However, the method disclosed in Patent Document 1 has a problem in that the cleaning operation is hindered because the sensor is disposed at the tip of the head nozzle. Moreover, since the pressure sensor is provided, the cost of the apparatus cannot be avoided.

  Furthermore, in the method of Patent Document 2, when the protrusion amount is set to be large, the contact pressure is initially excessively larger than necessary and the durability is shortened. The cleaning performance of the nozzle surface is maintained, but excessive stress is applied to the nozzle surface. A water repellent film is formed on the nozzle surface for the purpose of preventing ink sticking and improving the cleaning property. Excessive stress is applied to the water repellent film, and wear of the water repellent film is advanced. As a result, the durability of the entire recording apparatus is low. The same applies to the wiping speed.

  The present invention is for solving these problems, and the capping state of the recording head can be set to an optimum state with a simple configuration without disturbing the operation of the maintenance / recovery device, and excessive stress is applied to the nozzle surface. It is an object of the present invention to provide a recording apparatus that does not cause deterioration of the cleaning performance of the nozzle surface over time without giving.

  In order to solve the above problems, the recording apparatus of the present invention ejects ink droplets onto a recording medium from nozzles formed on the nozzle surface of a recording head using piezoelectric elements as pressure generating elements. The recording apparatus of the present invention includes a cap that contacts the nozzle surface of the recording head to seal the nozzle surface, and a contact pressure when the cap contacts the nozzle surface of the recording head. It has a feature in that it has detection means for detecting it as a change. Therefore, it becomes possible to know the contact state of the recording head of the cap, and since a pressure generating element that discharges ink droplets is used as a sensor that knows the contact state, the wiping operation is not hindered, and a new It is possible to avoid increasing the cost of the apparatus without increasing the number of parts.

  In addition, the contact pressure adjusting means for adjusting the contact pressure when the cap is in contact with the nozzle surface of the recording head based on the detection output of the detection means is desired so that the contact pressure is desired with a simple apparatus configuration. It is easy to manage to the value of.

  Further, the detecting means detects a change in capacitance of each of the plurality of piezoelectric elements to detect a contact pressure at a plurality of locations when the cap is in contact with the nozzle surface of the recording head, and a difference between the contact pressures is detected. When the predetermined range is exceeded, it is determined that the normal capping operation is not performed, and the capping operation is performed again. Therefore, it is possible to easily detect that the capping operation has failed due to an accidental external force such as vibration or impact, and to avoid one-side contact etc., and it is possible to perform the recovery operation appropriately. The reliability of the device is improved.

  The detecting means detects a change in capacitance of each of the plurality of piezoelectric elements to detect a contact pressure at a plurality of locations when the cap is in contact with the nozzle surface of the recording head. When the predetermined value is exceeded, it is determined that there is foreign matter on the nozzle surface of the recording head and the nip portion of the cap is in contact with the foreign matter, and the capping operation is canceled and a predetermined maintenance operation is performed. Accordingly, the foreign matter at the cap contact position of the recording head appears as a detection output of the contact state, and appropriate maintenance can be performed by performing a predetermined maintenance operation such as cleaning in accordance with the detection output.

  Further, the recording apparatus of the present invention moves relative to the recording head and abuts against the nozzle surface to wipe the nozzle surface, and the wiper when the wiper is in contact with the nozzle surface of the recording head. It is characterized by having a detecting means for detecting the contact pressure as a change in capacitance of the piezoelectric element. Therefore, it can be determined by a simple method whether or not the contact pressure of the wiper in the wiping of the recording apparatus is appropriate.

  Further, by having a protrusion amount adjusting means for adjusting the protrusion amount on the scanning track when the wiper performs the wiping operation based on the detection output of the detecting means, the wiper protrusion amount can be set to a desired value with a simple device configuration. Easy to manage.

  Furthermore, when the wiper performs the wiping operation on the nozzle surface, the protrusion amount adjusting means samples the change in the capacitance of the piezoelectric element from the start of wiping to the completion of wiping, and determines the protrusion amount of the wiper when wiping the nozzle surface according to the detection output. Change over time. Therefore, even when the distance between the wiper and the nozzle surface at the time of wiping varies, more optimal wiping control can be performed with a simple method without particularly increasing the apparatus cost.

  In addition, by having a speed adjusting means for adjusting the relative speed on the scanning orbit at the time of wiping with respect to the recording head based on the detection output of the detecting means, the relative speed on the scanning orbit at the time of wiping can be reduced with a simple device configuration. Management to a desired value can be easily realized.

  Furthermore, when the wiper performs a wiping operation on the nozzle surface, the speed adjusting means samples the change in the capacitance of the piezoelectric element from the start of wiping to the completion of wiping and temporally determines the carriage speed at the time of wiping the nozzle surface according to the detection output. Change. Therefore, even when the distance between the wiper and the nozzle surface at the time of wiping varies, more optimal wiping control can be performed with a simple method without particularly increasing the apparatus cost.

  The detecting means detects a change in capacitance of each of the plurality of piezoelectric elements to detect a contact pressure at a plurality of locations when the wiper performs a wiping operation on the nozzle surface, and a difference between the contact pressures exceeds a predetermined range. If it is determined that the normal wiping operation is not performed, the wiping operation is performed again. Therefore, it is possible to easily detect that a normal wiping operation is not performed due to one-side contact or the like due to an accidental external force such as vibration or impact, and the wiping operation can be performed again, thereby improving the reliability of the apparatus. .

  According to the recording apparatus of the present invention, it is possible to know the contact state of the recording head of the cap. In addition, since a pressure generating element that ejects ink droplets is used as a sensor for knowing the contact state, the wiping operation is not hindered and the cost of the apparatus does not increase. Further, it is possible to determine whether or not the contact pressure of the wiper in the wiping of the recording apparatus is appropriate by a simple method.

It is the perspective view which looked at the recording device of the present invention from the front. It is a side view which shows the outline | summary of the mechanism part of the recording device of this invention. It is a top view which shows the principal part of the mechanism part of the recording device of this invention. It is a top view which shows the principal part structure of the maintenance recovery apparatus which concerns on this invention. It is a schematic side view which shows the mechanism structure of the maintenance recovery apparatus of this invention. FIG. 5 is a right side view of FIG. 4. It is a side view which shows the structure of a cap holding | maintenance raising / lowering mechanism part. It is a front view which shows the structure of a cap holding | maintenance raising / lowering mechanism part. FIG. 3 is a cross-sectional view illustrating a configuration of a droplet discharge head that constitutes a recording head in a recording apparatus. FIG. 3 is a schematic cross-sectional view illustrating a state where a cap is in contact with a nozzle surface of a recording head of the recording apparatus of the present invention. FIG. 6 is a characteristic diagram illustrating a relationship between a contact pressure of a cap member with respect to a nozzle surface of a recording head and a capacitance value detected by each piezoelectric element. FIG. 4 is a circuit diagram illustrating a circuit configuration of a piezoelectric element of a recording head, a circuit of a driving IC, and a capacitance detection circuit. It is a wave form diagram which shows the output of each part in the state controlled so that the specific 1ch piezoelectric element and resistance for a detection may energize. It is a schematic sectional drawing which shows the state capped in the state where the contact pressure by the side of one piezoelectric element is insufficient. FIG. 4 is a schematic cross-sectional view illustrating a state in which foreign matter is attached to a nip portion when a cap member is in contact with a nozzle surface of a recording head. FIG. 6 is a characteristic diagram showing a state of sensing output in each piezoelectric element when a foreign object is on the nozzle surface of the recording head. FIG. 6 is a circuit diagram illustrating another circuit configuration of a piezoelectric element of a recording head, a circuit of a driving IC, and a capacitance detection circuit. FIG. 3 is a schematic cross-sectional view illustrating a state where a wiper is in contact with a nozzle surface of a recording head. FIG. 19 is a characteristic diagram showing a normalized capacitance value when the contact pressure when the wiper is on points A to C in FIG. 18 and the contact pressure when the contact pressure of the piezoelectric element is 0 is 1. It is a characteristic view which shows the relationship between the wiper and contact pressure as suitable conditions. When each channel capacitance value of one row of the piezoelectric elements of the recording head before the wiping operation is 1, the wiper protrusion amount is a relative capacitance value at an upper limit value (2.0 mm) and a lower limit value (1.0 mm). It is a figure which shows the relationship between the relationship, the appropriate range and contact speed of contact pressure, and contact pressure.

  FIG. 1 is a perspective view of the recording apparatus of the present invention as viewed from the front. The recording apparatus 100 of the present invention shown in FIG. 1 includes an apparatus main body 101, a paper feed tray 102 for loading paper mounted on the apparatus main body 101, and a detachably mounted on the apparatus main body 101 to record images ( And a paper discharge tray 103 for stocking the formed paper. Further, a cartridge loading for loading an ink cartridge that protrudes from the front surface to the front side of the apparatus main body 101 and is lower than the upper surface is provided at one end of the front surface of the apparatus main body 101 (side of the paper supply / discharge tray section). The cartridge loading unit 104 is provided with an operation / display unit 105 such as operation buttons and a display.

  The cartridge loading unit 104 stores a plurality of recording liquids (inks) that are different color materials, such as black (K) ink, cyan (C) ink, magenta (M) ink, and yellow (Y) ink. Ink cartridges 110k, 110c, 110m, and 110y (referred to as “ink cartridge 110” when the colors are not distinguished) are recording liquid cartridges serving as recording liquid storage units from the front side to the rear side of the apparatus main body 101. A front cover (cartridge cover) 106 that is opened when the ink cartridge 110 is attached or detached is provided on the front side of the cartridge loading unit 104 so as to be openable and closable. Further, the ink cartridges 110k, 110c, 110m, and 110y are configured to be loaded side by side in the horizontal direction in a vertically placed state.

  Further, the operation / display unit 105 has the remaining amounts of the ink cartridges 110k, 110c, 110m, and 110y for the respective colors at the arrangement positions corresponding to the installation positions (arrangement positions) of the ink cartridges 110k, 110c, 110m, and 110y for the respective colors. The remaining amount display sections 111k, 111c, 111m, and 111y for each color for displaying the near end and the end are arranged. Further, the operation / display unit 105 is also provided with a power button 112, a paper feed / print resume button 113, and a cancel button 114.

  Next, the mechanism part of the recording apparatus of the present invention will be described with reference to FIGS. 2 is a side view showing the outline of the mechanism, and FIG. 3 is a plan view of the main part.

  In the mechanism of the recording apparatus of the present invention, the carriage 133 is slidably held in the main scanning direction by a guide rod 131 and a stay 132 which are guide members horizontally mounted on the left and right side plates 121A and 121B constituting the frame 121. A main scanning motor (not shown) moves and scans in a direction indicated by an arrow (carriage scanning direction: main scanning direction) in FIG. 3 via a timing belt.

  As described above, the carriage 133 is provided with the recording head 134 including four droplet discharge heads that discharge ink droplets of yellow (Y), cyan (C), magenta (M), and black (Bk). A plurality of ink ejection openings are arranged in a direction crossing the main scanning direction, and are mounted with the ink droplet ejection direction facing downward.

  As an inkjet head constituting the recording head 134, a piezoelectric actuator such as a piezoelectric element, a thermal actuator that uses a phase change due to liquid film boiling using an electrothermal conversion element such as a heating resistor, and a metal phase change due to a temperature change. It is possible to use a shape memory alloy actuator to be used, an electrostatic actuator using an electrostatic force, or the like provided as pressure generating means for generating a pressure for discharging a droplet.

  A driver IC is mounted on the recording head 134 and is connected to a control unit (not shown) via a harness (flexible print cable) 122. The carriage 133 is equipped with a head tank 135 for each color for supplying ink of each color to the recording head 134. As described above, each color head tank 135 is supplementarily supplied with ink of each color from the ink cartridge 110 of each color mounted in the cartridge loading unit 104 via the ink supply tube 136 of each color. The cartridge loading 104 is provided with a supply pump unit 124 for feeding ink in the ink cartridge 110, and the ink supply tube 136 is locked to the rear plate 121C constituting the frame 121 in the middle of turning. It is held by the member 125.

  On the other hand, as a paper feeding unit for feeding the paper 142 stacked on the paper stacking unit (pressure plate) 141 of the paper feeding tray 102, a half-moon roller (feeding) that separates and feeds the paper 142 from the paper stacking unit 141 one by one. A separation pad 144 made of a material having a large friction coefficient is provided facing the paper roller 143 and the paper feed roller 143, and the separation pad 144 is urged toward the paper feed roller 143 side.

  In order to feed the sheet 142 fed from the sheet feeding unit to the lower side of the recording head 134, a guide member 145 for guiding the sheet 142, a counter roller 146, a transport guide member 147, and a tip pressure roller. And a holding belt 148 that is a conveying means for electrostatically attracting the fed paper 142 and conveying it at a position facing the recording head 134.

  The conveyor belt 151 is an endless belt, and is configured to wrap around the conveyor roller 152 and the tension roller 153 and circulate in the belt conveyance direction (sub-scanning direction). Further, a charging roller 156 that is a charging unit for charging the surface of the transport belt 151 is provided. The charging roller 156 is disposed so as to come into contact with the surface layer of the conveyor belt 151 and to rotate following the rotation of the conveyor belt 151. Further, a guide member 157 is disposed on the back side of the conveyance belt 151 so as to correspond to a printing area by the recording head 134.

  The transport belt 151 rotates in the belt transport direction of FIG. 3 when the transport roller 152 is rotationally driven through timing by a sub-scanning motor (not shown).

  Further, as a paper discharge unit for discharging the paper 142 recorded by the recording head 134, a separation claw 161 for separating the paper 142 from the transport belt 151, a paper discharge roller 162, and a paper discharge roller 163 are provided. A paper discharge tray 103 is provided below the paper discharge roller 162.

  A double-sided unit 171 is detachably attached to the back surface of the apparatus main body 101. The duplex unit 171 takes in the paper 142 returned by the reverse rotation of the transport belt 151, reverses it, and feeds it again between the counter roller 146 and the transport belt 151. The upper surface of the duplex unit 171 is a manual feed tray 172.

  Further, as shown in FIG. 3, a maintenance / recovery mechanism 181 including a recovery means for maintaining and recovering the nozzle state of the recording head 134 is arranged in the non-printing area on one side of the carriage 133 in the scanning direction. Yes.

  The maintenance / recovery mechanism 181 includes cap members (hereinafter referred to as “caps”) 182a to 182d (hereinafter referred to as “caps 182” when not distinguished) for capping each nozzle surface of the recording head 134, and nozzle surfaces. A wiper blade 183 that is a blade member for wiping the ink, and an empty discharge receiver 184 that receives liquid droplets when performing empty discharge for discharging liquid droplets that do not contribute to recording in order to discharge the thickened recording liquid. ing. Here, the cap 182a is a suction and moisture retention cap, and the other caps 182b to 182d are moisture retention caps.

  Then, the waste liquid of the recording liquid generated by the maintenance / recovery operation by the maintenance / recovery mechanism 181, the ink discharged to the cap 182, the ink attached to the wiper blade 183 and removed by the wiper cleaner 185, and the idle ejection to the idle ejection receptacle 194 The discharged ink is discharged and stored in a waste liquid tank (not shown).

  Further, as shown in FIG. 3, in the non-printing area on the other side in the scanning direction of the carriage 133, idle discharge is performed to discharge liquid droplets that do not contribute to recording in order to discharge the recording liquid thickened during recording or the like. An empty discharge receiver 188 for receiving the droplets is disposed, and the empty discharge receiver 188 is provided with an opening 189 along the nozzle row direction of the recording head 134.

  In the recording apparatus of the present invention configured as described above, the sheets 142 are separated and fed one by one from the sheet feeding tray 102, and the sheet 142 fed substantially vertically upward is guided by the guide 145, and the conveyance belt 151. It is sandwiched between the counter roller 146 and conveyed. Further, the leading end is guided by the conveying guide 137 and pressed against the conveying belt 151 by the leading end pressing roller 149, and the conveying direction is changed by about 90 °.

  At this time, a charging voltage pattern in which a positive output and a negative output are alternately repeated from the AC bias supply unit of the control circuit (not shown) to the charging roller 156, that is, an alternating voltage is applied and the conveying belt 151 is alternating, That is, plus and minus are alternately charged in a band shape with a predetermined width in the sub-scanning direction which is the circumferential direction. When the sheet 142 is fed onto the conveying belt 151 that is alternately charged with plus and minus, the sheet 142 is attracted to the conveying belt 151, and the sheet 142 is conveyed in the sub-scanning direction by the circumferential movement of the conveying belt 151.

  Therefore, by driving the recording head 134 according to the image signal while moving the carriage 133 in the main scanning direction based on the main scanning position information by the linear encoder 137, the ink droplets are ejected onto the stopped paper 142. One line is recorded, and after the sheet 142 is conveyed by a predetermined amount, the next line is recorded. Upon receiving a recording end signal or a signal that the trailing edge of the sheet 142 has reached the recording area, the recording operation is terminated and the sheet 142 is discharged onto the discharge tray 103.

  During printing (recording) standby, the carriage 133 is moved to the maintenance / recovery mechanism 181 side, the recording head 134 is capped by the cap 182, and the nozzles are kept in a wet state, thereby preventing ejection failure due to ink drying. . Further, the recording liquid is sucked from the nozzle by a suction pump (not shown) with the recording head 134 capped by the cap 182 (referred to as “nozzle suction” or “head suction”), and the thickened recording liquid and bubbles are discharged. Perform recovery action. In addition, an idle ejection operation for ejecting ink not related to recording is performed before the start of recording or during recording. As a result, the stable ejection performance of the recording head 134 is maintained.

  Here, an outline of the configuration of the maintenance and recovery apparatus according to the present invention will be described with reference to FIGS. 4 is a plan view showing the configuration of the main part of the maintenance and recovery apparatus of the present invention, FIG. 5 is a schematic side view showing the mechanism configuration of the maintenance and recovery apparatus of the present invention, and FIG. 6 is a right side view of FIG.

  The frame 259 in the maintenance / recovery device 250 of the present invention is a wiping member including two cap holders 260a and 260b (cap holders 260 when not distinguished) and an elastic body as a cleaning means. A certain wiper blade 252 and a carriage lock 261 are held so as to be movable up and down (movable up and down). An empty discharge receiver 253 is disposed between the wiper blade 252 and the cap holder 260a, and the wiper blade 252 is a cleaning member for the empty discharge receiver 253 from the outside of the frame 258 in order to clean the wiper blade 252. A wiper cleaner 255 that is a cleaner means including a cleaner roller 256 that is a cleaning member to be pressed against the wiper cleaner 254 side is swingably held. The cap holders 260a and 260b hold two cap members 251a and 251b and cap members 251c and 251d, respectively, for capping the nozzle surfaces of the two recording heads 134, respectively.

  Here, a tubing pump (suction pump) 263, which is a suction means, is connected to the cap member 251a held by the cap holder 260a closest to the printing area via a flexible tube 262, and the other cap members 251b, The tubing pump 263 is not connected to 251c and 251d. That is, only the cap member 251a is a suction (recovery) and moisturizing cap, and the other cap members 251b, 251c, and 251d are all mere moisturizing caps. Therefore, when performing the recovery operation of the recording head 134, the recording head 134 that performs the recovery operation is selectively moved to a position where it can be capped by the cap member 251a.

  Further, a cam shaft 264 rotatably supported by the frame 259 is disposed below the cap holders 260a and 260b, and cap cams 265a and 265b for raising and lowering the cap holders 260a and 260b are arranged on the cam shaft 264. A wiper cam 266 for raising and lowering the wiper blade 252; a carriage lock cam 268 for raising and lowering the carriage lock 261 via the carriage lock arm 267; A roller 269 as a rotating body that is a landing member and a cleaner cam 270 for swinging the wiper cleaner 255 are provided.

  Here, the cap member 251 is moved up and down by the cap cams 265a and 265b. The wiper blade 252 is moved up and down by the wiper cam 266. When the wiper cleaner 255 is lowered, the wiper cleaner 255 advances, and the wiper blade 252 moves downward while being sandwiched between the cleaner roller 256 of the wiper cleaner 255 and the wiper cleaner 255 of the idle discharge receiver 253. Ink adhering to 252 is scraped off into the idle ejection receptacle 253. The carriage lock 261 is urged upward (in the locking direction) by a compression spring (not shown), and is lifted and lowered via a carriage lock arm 267 driven by a carriage lock cam 268.

  In order to rotationally drive the tubing pump 263 and the cam shaft 264, the rotation of the motor 271 is meshed with the motor gear 272 provided on the motor shaft 271a, and the pump gear 273 provided on the pump shaft 263a of the tubing pump 263 is further engaged. An intermediate gear 277 with a one-way clutch 276 is engaged with an intermediate gear 274 integral with the H.273 via an intermediate gear 275, and the intermediate gear 278 coaxial with the intermediate gear 277 is fixed to the camshaft 264 via the intermediate gear 279. The cam gear 280 is engaged. An intermediate shaft 281 that is a rotation shaft of the intermediate gears 277 and 278 with the clutch 276 is rotatably held by the frame 259.

  The cam shaft 264 is provided with a home position sensor cam 282 for detecting the home position, and the home position sensor (not shown) provided in the maintenance / recovery device 250 provides a home position when the cap member 251 reaches the lowest end. A position lever (not shown) is operated, and the sensor is opened to detect the home position of the motor 271 (other than the tubing pump 263). In addition, when the power is turned on, it moves up and down regardless of the position of the cap member 251 (cap holder 260), does not detect the position until the start of movement, and after detecting the home position (upward) of the cap member 251, Move the set amount to the bottom end. Thereafter, the carriage moves left and right, returns to the cap position after position detection, and the recording head 134 is capped. The lifting / lowering operation of each part has been described above, but the lifting position (height) of each component is controlled by controlling the rotation of the motor 271 that is a drive source.

Next, details of the cap holding mechanism and the lifting mechanism will be described with reference to FIG. 5, FIG. 7 of the side view of the cap holding lifting mechanism section, and FIG. 8 of the front view.
A cap holder 260a, which is one of the constituent members of the cap holding mechanism, includes a holder 284 that holds the cap 251a and the cap 251b (collectively referred to as the cap 251A) so as to be movable up and down, a bottom surface of the holder 284, and a bottom portion of the cap 251A. And a slider 286 that holds the holder 284 so as to be movable in the front-rear direction (arrangement direction of the nozzles of the recording head 134). The cap 251A is inserted into the guide groove 283a (not shown) of the holder 284 so that the guide pins 283a provided at both ends can be moved up and down, and the guide shaft 283b provided on the bottom surface is inserted into the holder 284 so as to move up and down. It is mounted so that it can move. A spring 285 interposed between the cap 251A and the holder 284 urges the caps 251a and 251b upward (in the direction of pressing toward the nozzle surface during capping). The slider 286 is configured such that the guide pins 287 and 288 provided at the front and rear ends are slidably fitted into guide grooves 289 formed in the frame 259 so that the slider 286, the holder 284, and the cap 251A as a whole can move up and down.

  Then, the cam pin 290 provided on the lower surface of the slider 286 is fitted into a cam groove (not shown) of the cap cam 265a, and the slider 286 is rotated by the rotation of the cap cam 265a that is synchronized with the rotation of the cam shaft 264 to which the rotation of the motor 271 is transmitted. The holder 284 and the cap 251A move up and down.

  Further, a slider 286 and a holder 284 are inserted through the suction cap 251a, and the tube 262 is wound around and connected from below the center position of the cap in the short direction of the cap 251a.

  The cap holder 260b for holding the caps 251c and 251d (collectively referred to as the cap 251B) and the configuration for moving the cap up and down are also the same as described above, and thus the description thereof is omitted. However, the tube 262 is not connected to the caps 251c and 251d.

  Thus, by driving the motor 271 that is one drive source, the cam shaft 264 that is one shaft rotates, and the cams 265a and 265b fixed to the cam shaft 264 are rotated by the rotation of the cam shaft 264. The cap 251A and the cap 251B move up and down.

  Next, an example of a droplet discharge head constituting the recording head in the recording apparatus will be described with reference to FIG. 1A is a cross-sectional view taken along the longitudinal direction of the liquid chamber of the droplet discharge head constituting the recording head in the recording apparatus of the present invention, and FIG. It is sectional drawing of the arrangement direction of a nozzle. The droplet discharge head 200 includes, for example, a flow channel plate 201 formed by anisotropic etching of a single crystal silicon substrate, a vibration plate 202 formed by, for example, nickel electroforming bonded to the lower surface of the flow channel plate 201, The nozzle plate 203 bonded to the upper surface of the flow path plate 201 is bonded and stacked, and the nozzle communication path 205 and the liquid chamber 206, which are flow paths through which the nozzles 204 for discharging liquid droplets (ink droplets) communicate with each other, An ink supply port 208 communicating with a common liquid chamber 207 for supplying ink to the chamber 206 is formed. Further, two rows as electromechanical conversion elements which are pressure generating means (actuator means) for pressurizing the ink in the liquid chamber 206 by deforming the vibration plate 202 (only one row is shown in FIG. 9B). And the base substrate 210 to which the piezoelectric element 209 is bonded and fixed.

  Here, there are 192 ch driven piezoelectric elements in one row, and one recording head has 384 ch. Furthermore, the arrangement direction of the nozzles in one row is a direction perpendicular to the moving type scanning direction of the carriage. A support column 211 is provided between the piezoelectric elements 209. The column portion 211 is a portion formed at the same time as the piezoelectric element 209 by dividing the piezoelectric element member. However, since the driving voltage is not applied, the column portion 211 is a simple column.

  Further, an FPC cable 212 equipped with a drive circuit (drive IC) (not shown) is connected to the piezoelectric element 209. The drive IC includes a capacitance detection circuit described later. The peripheral portion of the diaphragm 202 is joined to the frame member 213, and the frame member 213 has a through-hole 214 that houses an actuator unit composed of the piezoelectric element 209, the base substrate 210, etc. In addition, an ink supply hole 215 for supplying ink from the outside to the common liquid chamber 207 is formed. The frame member 213 is formed by injection molding with a thermosetting resin such as an epoxy resin or polyphenylene sulfite, for example.

  Here, the flow path plate 201 is formed by, for example, subjecting the single crystal silicon substrate having a crystal plane orientation (110) to an anisotropic etching using an alkaline etching solution such as an aqueous potassium hydroxide solution (KOH), so that the nozzle communication path 205, Although a recess or a hole serving as the liquid chamber 206 is formed, it is not limited to a single crystal silicon substrate, and other stainless steel substrates, photosensitive resins, and the like can also be used. The diaphragm 202 is formed from a nickel metal plate, and is manufactured by, for example, an electroforming method (electroforming method). In addition, a metal plate or a joining member between a metal and a resin plate may be used. it can. The piezoelectric element 209 and the support column 211 are bonded to the vibration plate 202 with an adhesive, and the frame member 213 is bonded with an adhesive. The nozzle plate 203 forms a nozzle 204 having a diameter of 10 to 30 μm corresponding to each liquid chamber 206 and is bonded to the flow path plate 201 with an adhesive. The nozzle plate 203 has a water repellent layer formed on the outermost surface of a nozzle forming member made of a metal member with a required layer interposed therebetween. The surface of the nozzle plate 203 is the nozzle surface described above. The piezoelectric element 209 is a stacked piezoelectric element (here, PZT) in which piezoelectric materials 216 and internal electrodes 217 are alternately stacked. An individual electrode 218 and a common electrode 219 are connected to the internal electrodes 217 drawn to alternately different end faces of the piezoelectric element 209. In this embodiment, the ink in the liquid chamber 206 is pressurized using the displacement in the d33 direction as the piezoelectric direction of the piezoelectric element 209, but the pressure is applied using the displacement in the d31 direction as the piezoelectric direction of the piezoelectric element 209. A configuration may be adopted in which the ink in the liquid chamber 206 is pressurized.

  Alternatively, a structure in which one row of piezoelectric elements 209 is provided on one substrate 210 may be employed. In the droplet discharge head configured as described above, for example, when the voltage applied to the piezoelectric element 209 is lowered from the reference potential, the piezoelectric element 209 contracts, and the vibration plate 202 descends to expand the volume of the liquid chamber 206. As a result, ink flows into the liquid chamber 206, and then the voltage applied to the piezoelectric element 209 is increased to extend the piezoelectric element 209 in the stacking direction, and the diaphragm 202 is deformed in the nozzle 204 direction to change the volume of the liquid chamber 206. / By contracting the volume, the recording liquid in the liquid chamber 206 is pressurized, and droplets of the recording liquid are ejected (jetted) from the nozzle 204. Then, by returning the voltage applied to the piezoelectric element 209 to the reference potential, the vibration plate 202 is restored to the initial position, and the liquid chamber 206 expands to generate a negative pressure. The recording liquid is filled in 206.

  Therefore, after the vibration of the meniscus surface of the nozzle 204 is attenuated and stabilized, the operation proceeds to the next droplet discharge. Note that the driving method of the head is not limited to the above example (drawing-pushing), and striking or pushing can be performed depending on the direction of the drive waveform.

  Next, detection of the capping contact state of the recording head of the recording apparatus of the present invention will be described with reference to FIGS. FIG. 10 is a schematic cross-sectional view showing a state where the cap is in contact with the nozzle surface of the recording head. FIG. 10 is drawn in the direction in which the actual recording head is mounted on the carriage and in the direction upside down. There are two rows of piezoelectric elements in the droplet discharge head 200, one being 209a and the other being 209b.

  The cap member 251 with respect to the recording head 200 has an appropriate parallel state of the nozzle surface and the nip portion around the cap. FIG. 10 shows an appropriate state. First, when the cap member 251 in FIG. 10 contacts the nozzle plate 203, the contact pressure is transmitted to the nozzle plate 203, the flow path plate 201, the vibration plate 202, and the piezoelectric element 209 in order. The capacitance value of each piezoelectric element 209 changes depending on the transmitted pressure.

  FIG. 11 is a characteristic diagram showing the relationship between the contact pressure of the cap member against the nozzle surface of the recording head and the capacitance value detected by each piezoelectric element. The capacity value indicates a standardized capacity value when the capacity value is 1 when the contact pressure is 0 (when the cap is not in contact with the nozzle surface). As can be seen from the figure, if the change in capacity from the initial value is known, the contact pressure of the cap near the nozzle can be known.

  FIG. 12 is a circuit diagram showing the circuit configuration of the piezoelectric element of the recording head, the circuit of the drive IC, and the capacitance detection circuit. The piezoelectric element is expressed as a capacitive component. The analog switches 301 and 302 integrated in the drive IC are connected to the piezoelectric element 209 of each channel. The analog switches 301 are turned on when the analog switch 301 performs the ejection operation, and the drive waveform of the resistance value does not deteriorate. Here, the resistance when ON is Rond = 300Ω. The analog switch 302 is for detecting the capacitance and is turned ON only when detecting the capacitance. Here, the resistance when ON is Rone = 1 kΩ. The opening / closing operation of each switch is controlled via the control circuit 300 of the drive IC by an output from a controller (not shown) on the recording apparatus main body side. The resistor 303 (Re) is a resistor for capacitance detection, and one terminal of the resistor 303 (Re) is connected to the drive waveform generation circuit output 304, one terminal of the resistor 305 (Reh), and the common input side of the analog switch 301. The other terminal of the resistor 303 (Re) is connected to the common input side of the analog switch 302, and the resistance value is 10 kΩ. The resistors 305 (Reh), 306 (Rem), and 307 (Rel) each divide the drive waveform generation output voltage, and the ratio of the values is Reh: Rem: Rel = 2: 8: 1. In addition, each value is increased to a value that does not affect the resistance (Re) 303 when the analog switch 302 is turned on. Here, Reh = 200 kΩ, Rem = 800 kΩ, and Rel = 100 kΩ. The drive waveform generation output voltage is divided by these resistors and inputted to the comparators 308 and 309, and the input drive waveform output response of the CR circuit constituted by the detection resistor 303 and the piezoelectric element 209 performing the detection, and To be compared. The comparator 308 detects whether or not the early rising waveform has reached 10% of the amplitude when the drive waveform generation circuit 304 is output, and the comparator 309 similarly detects whether or not the value of 90% is detected. The logic element 310 performs a logic operation on both comparator outputs.

  Here, the operation for detecting the capacity, that is, the operation for detecting the contact pressure will be described with reference to FIG. FIG. 13 shows the output of each part in a state where a specific 1ch piezoelectric element and a detection resistor are controlled to be energized. In the figure, VCOM is the output of the drive waveform generation circuit 304 of FIG. 12, Ve is the voltage on the piezoelectric element side of the detection resistor, and Vep is the output of the logic element 310. First, the drive waveform generation circuit 304 outputs an early signal whose rise is within 1 usec. At this time, the voltage waveform on the piezoelectric element 209 side of the detection resistor 303 indicates the response of the CR circuit. The output Vep of the logic element 310 is a pulse having a width of 10% -90% time Te of the rise of the Ve waveform. Here, Te [sec] is used to measure the pulse width by receiving this pulse on the main body controller side. Here, since the time constant (Rone + Re) · C and the pulse width Te have the relationship of the following expression, the value of C can be obtained on the controller side. If the value of C can be known with and without contact pressure, the contact pressure can be detected.

  Te≈2.2 × (Rone + Re) · C

  Here, the principle of the capping operation in the recording apparatus of the present invention will be described. Since the displacement direction of the piezoelectric element 209 and the direction of the contact pressure are substantially parallel, the capacity value increases as the contact pressure increases. Here, the capacitance of the piezoelectric element 209 per channel is 1 n [F]. When the contact pressure for capping is appropriate, the recording apparatus according to the present invention has a value of 1.0 [N] or more. In the recording apparatus of the present invention, if the minimum value of the capacity value of 384ch detected in one recording head is 1.0 [N] or more, it is determined that the recording head is appropriately capped.

  Next, the capping operation will be described. The carriage moves to a capping position determined by a predetermined movement. Subsequently, the maintenance / recovery device starts to move the cap member 251 up and down. At the same time, the piezoelectric element 209 is moved up and down while detecting the capacitance. The detection is performed for all the channels, and when the minimum detection output reaches a capacity corresponding to 1.0 [N], the raising / lowering operation is stopped and the capping operation is completed. It should be noted that when performing capacity detection in the capping operation, ch is not performed for all the channels, but detection is performed only at the end and center, and detection is performed for a specific channel such as detection every other channel. Conceivable. The detection time is shortened by setting the detection operation for only a specific channel.

  Next, the case where the urging state of the cap member is changed due to vibration, external force or the like during the capping operation and an appropriate capping state is not achieved will be described. FIG. 14 shows a state in which it is tilted and capped in a state where the contact pressure on one piezoelectric element side is insufficient. In the figure, the same reference numerals as those in FIG. 10 denote the same components. Such a capping state is not appropriate capping because the air in the cap communicates with the outside and the nozzle surface may be dried. In the state of FIG. 14, the piezoelectric element 209a is the detection output at point A in FIG. 11, and the piezoelectric element 209b is the detection output at point B in FIG. The recording apparatus controls to perform the capping operation again when such a state is detected. Also, the difference in detection output between the piezoelectric element 209a row and the piezoelectric element 209b row during capping is monitored, and the capping operation is performed when the difference is detected at a certain value or more regardless of whether each output is within the proper range. May be re-executed.

  Next, the operation in the case where foreign matter is attached to the nip portion when the cap member comes into contact with the nozzle surface of the recording head will be described with reference to FIGS. In FIG. 15, when there is a foreign object 401, the contact pressure of the corresponding part increases. FIG. 16 is a characteristic diagram showing the state of the sensing output in each piezoelectric element at this time. In FIG. 16, foreign matter is observed as the difference δ between the lowest value and the highest value. When the recording apparatus detects this state, the maintenance of the nozzle surface of the recording head is activated to perform cleaning. When the cleaning operation is performed and foreign matter is removed, an appropriate capping operation can be performed. In the above embodiment, the pressure is detected using the piezoelectric element 209 related to the droplet discharge in FIG. 10, but it is also conceivable to detect the pressure using the column part 211. When using the column part, wiring is performed to each of the piezoelectric element 209 of the driving unit and the piezoelectric element 311 of the column unit 211 by the FPC cable 212. At this time, the drive IC and the capacitance detection circuit are as shown in FIG. The circuit operation for capacitance detection is the same as the operation in FIG. In such a configuration, detection while discharging is also possible.

  Next, contact pressure detection at the time of wiper contact of the recording head in the recording apparatus of the present invention will be described with reference to FIGS. FIG. 18 is a schematic cross-sectional view showing a state where the wiper is in contact with the nozzle surface of the recording head. In FIG. 18, the actual recording head is drawn in the direction in which the head is mounted on the carriage and upside down. Further, although the wiper is moving on the recording head, the carriage is actually moving on the protruding wiper. In FIG. 18, the wiper 252 for the recording head is wiped in a direction perpendicular to the nozzle row. First, when the wiper 252 contacts the surface of the nozzle plate 203, the contact pressure is transmitted to the nozzle plate 203, the flow path plate 201, the vibration plate 202, and the piezoelectric element 209. The capacitance value of the piezoelectric element 209 changes depending on the transmitted pressure.

  FIG. 19 is a characteristic diagram showing normalized capacitance values when the contact pressure when the wiper is on points A to C in FIG. 18 and the capacitance value when the contact pressure of the piezoelectric element is 0 is 1. It is. As can be seen from FIG. 19, if the change in capacity from the initial value is known, the contact pressure of the ch can be known. Since the displacement direction of the piezoelectric element 209 and the direction of the contact pressure are substantially parallel, the capacitance value increases as the contact pressure increases. Here, the capacitance of the piezoelectric element 209 per channel is 1 nF. The contact pressure has a range that is considered appropriate, and 1.0 to 1.5 [N] is an appropriate range in this recording apparatus. The change in the capacity with respect to the contact pressure differs for each of the points A to C in FIG. 18 because the pressure is transmitted better at the central portion in the longitudinal direction of the piezoelectric element. This is because the point C is highly rigid and has a slightly higher pressure transmission than the central portion. Here, the wiping performance as a whole includes the wiping speed in addition to the contact pressure. In the recording apparatus of the present invention, the relative speed between the wiper 252 and the recording head is appropriate in the range of 95 mm / sec to 105 mm / sec under the appropriate contact pressure. Further more preferable conditions are points on a straight line shown in FIG.

  Here, optimization of the wiping operation of the recording apparatus of the present invention will be described with reference to FIG. FIG. 21 shows the relative wiper protrusion amount at the upper limit value (2.0 mm) and the lower limit value (1.0 mm), where each channel capacitance value of one row of piezoelectric elements of the recording head before the wiping operation is 1. FIG. 20 illustrates the relationship between the capacitance values, the appropriate range of the contact pressure in FIG. 19, and the relationship between the optimum speed and the contact pressure in FIG. When the setting of the recording apparatus is such, if the setting is brought to the upper limit of 2 mm, appropriate wiping can be performed. Further, the average capacity value of the recording head is employed, and the relative speed of wiping at the protrusion amount setting of 2 mm can be determined from the straight line of the optimum condition as shown in FIG. If the abutment pressure is different at each ABC point on the surface of the nozzle plate even if the protrusion amount is constant, the speed may be changed for each point to obtain the optimum condition. The optimum condition may be obtained by sequentially changing. It is also conceivable to obtain optimum conditions by simultaneously changing both the protrusion amount and the relative speed. These optimum conditions are preferably set regularly in the recording apparatus. Durability as a recording apparatus is improved by periodically setting conditions.

  The present invention is not limited to the above-described embodiments, and various modifications, substitutions, and applications are possible as long as they are described within the scope of the claims.

100; Recording device, 209; Piezoelectric element, 250; Maintenance / recovery device,
251; Cap member, 252; Wiper.

Utility Model Registration No. 2,514,548 JP 2006-224331 A

Claims (10)

In a recording apparatus for ejecting ink droplets from a nozzle formed on a nozzle surface of a recording head using a piezoelectric element as a pressure generating element to a recording medium,
A cap that contacts the nozzle surface of the recording head and seals the nozzle surface;
And a detecting means for detecting a contact pressure when the cap is in contact with the nozzle surface of the recording head as a change in capacitance of the piezoelectric element.   The recording apparatus according to claim 1, further comprising a contact pressure adjusting unit that adjusts a contact pressure when the cap is in contact with the nozzle surface of the recording head based on a detection output of the detection unit. .   The detecting means detects a change in capacitance of each of the plurality of piezoelectric elements to detect a contact pressure at a plurality of locations when the cap is in contact with the nozzle surface of the recording head. 2. The recording apparatus according to claim 1, wherein when the difference exceeds a predetermined range, it is determined that a normal capping operation is not performed, and the capping operation is performed again.   The detecting means detects a change in capacitance of each of the plurality of piezoelectric elements to detect a contact pressure at a plurality of locations when the cap is in contact with the nozzle surface of the recording head. When the pressure exceeds a predetermined value, it is determined that there is a foreign matter on the nozzle surface of the recording head and the nip portion of the cap is in contact with the foreign matter, and the capping operation is released to perform a predetermined maintenance operation. The recording apparatus according to claim 1. In a recording apparatus for ejecting ink droplets from a nozzle formed on a nozzle surface of a recording head using a piezoelectric element as a pressure generating element to a recording medium,
A wiper that moves relative to the recording head and contacts the nozzle surface to wipe the nozzle surface;
And a detecting unit configured to detect a contact pressure when the wiper is in contact with a nozzle surface of the recording head as a change in capacitance of the piezoelectric element.   6. The recording apparatus according to claim 5, further comprising a protruding amount adjusting unit that adjusts a protruding amount onto a scanning track when the wiper performs a wiping operation based on a detection output of the detecting unit.   When the wiper performs a wiping operation on the nozzle surface, the protrusion amount adjusting means samples the change in the capacitance of the piezoelectric element from the start of wiping to the completion of wiping, and determines the protrusion amount of the wiper when wiping the nozzle surface according to the detection output. The recording apparatus according to claim 6, wherein the recording apparatus is changed with time.   8. The recording according to claim 5, further comprising a speed adjusting unit that adjusts a relative speed on a scanning trajectory at the time of wiping with respect to the recording head based on a detection output of the detecting unit. apparatus.   When the wiper performs a wiping operation on the nozzle surface, the speed adjusting means samples the change in the capacitance of the piezoelectric element from the start of wiping to the completion of wiping and temporally determines the carriage speed at the time of wiping the nozzle surface according to the detection output. 9. The recording apparatus according to claim 8, wherein the recording apparatus is changed.   The detecting means detects a change in capacitance of each of the plurality of piezoelectric elements to detect a contact pressure at a plurality of locations when the wiper performs a wiping operation on the nozzle surface, and a difference between the contact pressures falls within a predetermined range. The recording apparatus according to any one of claims 5 to 9, wherein when exceeding, it is determined that a normal wiping operation is not performed, and the wiping operation is performed again.

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