JP5776457B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus provided with a recording head for discharging droplets.

  As an image forming apparatus such as a printer, a facsimile, a copying apparatus, a plotter, and a complex machine of these, for example, a liquid discharge recording type image forming apparatus using a recording head composed of a liquid discharge head (droplet discharge head) for discharging droplets Inkjet recording apparatuses are known.

  As such an image forming apparatus, for example, a plurality of replaceable main tanks (ink cartridges) that store ink to be supplied to recording heads that eject droplets of different colors, and liquids of each color are supplied from the main tank. Some have a plurality of head tanks of each color for supplying ink of the recording head.

  In addition, it has a maintenance / recovery mechanism that maintains and restores the performance of the recording head. The maintenance / recovery mechanism usually has a suction cap for capping the nozzle surface of the recording head and a suction pump connected to the suction cap.

  Further, there is a head tank that includes an openable and closable air release mechanism that opens the interior to the atmosphere, and the air release mechanism is driven by an air release drive means on the apparatus main body side.

  By the way, when driving a plurality of liquid feed pumps and suction pumps, if a drive motor is provided as a drive source for each pump, the apparatus becomes large and the cost increases.

  Therefore, conventionally, in a state in which the sun gear rotated in the first direction and the second direction by the rotational power of the selective drive mechanism, revolves around the sun gear according to the rotation of the sun gear, and the revolution is restricted. A planetary gear that rotates according to the rotation of the sun gear, and a pump that is arranged along the revolving trajectory of the planetary gear so that the planetary gear sequentially engages with the planetary gear when the planetary gear revolves according to the rotation of the sun gear in the first direction. A drive gear and a revolution regulating means for regulating the revolution of the planetary gear according to the rotation of the sun gear in the second direction at the meshing position with the pump drive gear, and more than two pumps are selectively selected by a single drive source What is driven is known.

Japanese Patent No. 4019694

  However, in the configuration using the sun gear and the planetary gear described above, it is difficult to operate independently without being limited by other pump drives, compared to the case where each pump is provided with a drive source, The drive direction (rotation direction) of the pump is limited to one direction. For example, there is a problem that it is difficult to apply when using a liquid feed pump that performs liquid feed and reverse feed.

  The present invention has been made in view of the above problems, and an object of the present invention is to enable a plurality of pumps and the like to be driven with a small degree of freedom with a small number of drive sources.

In order to solve the above problems, an image forming apparatus according to the present invention provides:
A recording head that ejects different types of droplets;
A plurality of head tanks for supplying liquid to the recording head;
A plurality of replaceable main tanks for storing liquid to be supplied to the recording head;
A plurality of liquid feed pumps for feeding the liquid from each main tank to the head tank, and for feeding back the liquid from the head tank to the main tank;
A first drive source for driving the plurality of liquid feed pumps;
A drive switching mechanism that selectively transmits the driving force of the first drive source to the plurality of liquid feeding pumps,
The drive switching mechanism is
A second drive source comprising a stepping motor;
A cam rotated by the second drive source;
A slider member that moves in a thrust direction in conjunction with rotation of the cam;
A switching gear to which the driving force of the first driving source is transmitted and moved by the slider member between a position engaging with a driving gear of the plurality of liquid feeding pumps and a position separating from the position.
By moving the switching gear, the driving force of the first driving source is selectively transmitted to the plurality of liquid feeding pumps,
Motor drive control means for driving and controlling the second drive source;
The cam is provided with a predetermined position detected portion for detecting a position where the cam is rotated by a predetermined angle from a predetermined home position,
Having detection means for detecting the predetermined position detected portion;
The motor drive control unit corrects the count value of the step number for the second drive source to the count value of the step number corresponding to the predetermined position when the detection unit detects the predetermined position detected portion.

  According to the image forming apparatus of the present invention, since the pump drive source and the power of the drive switching mechanism are separated, it is possible to drive a plurality of pumps or the like with a small number of drive sources with a degree of freedom.

FIG. 3 is a side explanatory view illustrating a mechanism unit of an example of an image forming apparatus according to the present invention. It is principal part plane explanatory drawing of the mechanism part. It is a typical plane explanatory view showing an example of a head tank. FIG. 4 is a schematic front explanatory view of FIG. 3. It is typical explanatory drawing with which it uses for description of the supply / discharge system in the same apparatus. It is typical explanatory drawing explaining an example of the tube pump which comprises the liquid feeding pump and suction pump of the embodiment. It is block explanatory drawing explaining the control part of the apparatus. It is typical explanatory drawing with which it uses for description of the drive switching mechanism in one Embodiment of this invention. It is a perspective explanatory view of a specific configuration of the drive switching mechanism. It is the perspective explanatory view which removed the cam part similarly. It is a perspective explanatory view of a cam and a slider member. It is typical explanatory drawing of the drive switching mechanism with which description of an example of the drive control of the 2nd drive source of the drive switching mechanism in this invention is provided. It is explanatory drawing similarly used for description of a cam position detection mechanism. It is explanatory drawing with which it uses for description of the relationship of the drive transmission object, a cam position (cam angle), the number of step pulses from the home position of a 2nd drive source, and the detection signal of a switching sensor. It is explanatory drawing with which it uses for description of the cam position detection mechanism in a comparative example. Detection of drive transmission target, cam position (cam angle), step pulse number from second drive source home position, and switching sensor for explanation of another example of drive control of second drive source of drive switching mechanism in the present invention It is explanatory drawing with which it uses for description of the relationship between signals.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. First, an example of an image forming apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is an explanatory side view for explaining the overall configuration of the image forming apparatus, and FIG. 2 is an explanatory plan view of a main part of the apparatus.

  This image forming apparatus is a serial type ink jet recording apparatus, and a carriage 33 is held movably in the main scanning direction by main and sub guide rods 31 and 32 which are guide members horizontally mounted on the left and right side plates 21A and 21B of the apparatus main body 1. The main scanning motor, which will be described later, moves and scans in the carriage main scanning direction via the timing belt.

  The carriage 33 is provided with recording heads 34a and 34b composed of liquid ejection heads for ejecting ink droplets of yellow (Y), cyan (C), magenta (M), and black (K). The “recording head 34” is arranged in a sub-scanning direction orthogonal to the main scanning direction, and the ink droplet ejection direction is directed downward.

  Each of the recording heads 34 has two nozzle rows. One nozzle row of the recording head 34a has black (K) droplets, the other nozzle row has cyan (C) droplets, and the recording head 34b has one nozzle row. One nozzle row ejects magenta (M) droplets, and the other nozzle row ejects yellow (Y) droplets.

  Further, the carriage 33 is equipped with head tanks 35a and 35b (referred to as “head tank 35” when not distinguished) for supplying ink of each color corresponding to the nozzle rows of the recording head 34. In the head tank 35, ink cartridges 10y, 10m, 10c, and 10k, which are main tanks of the respective colors that are detachably attached to the cartridge loading unit 4, are supplied from the ink pumps 24 through the supply tubes 36 of the respective colors. Of ink is replenished.

  On the other hand, as a paper feeding unit for feeding the papers 42 stacked on the paper stacking unit (pressure plate) 41 of the paper feeding tray 2, a half-moon roller (feeding) that separates and feeds the papers 42 one by one from the paper stacking unit 41. A separation pad 44 made of a material having a large friction coefficient is provided facing the paper roller 43) and the paper feed roller 43, and the separation pad 44 is urged toward the paper feed roller 43 side.

  In order to feed the paper 42 fed from the paper feeding unit to the lower side of the recording head 34, a guide member 45 for guiding the paper 42, a counter roller 46, a transport guide member 47, and a tip pressure roller. And a holding belt 48 which is a conveying means for electrostatically attracting the fed paper 42 and conveying it at a position facing the recording head 34.

  The transport belt 51 is an endless belt, and is configured to wrap around the transport roller 52 and the tension roller 53 and circulate in the belt transport direction (sub-scanning direction). Further, a charging roller 56 that is a charging unit for charging the surface of the transport belt 51 is provided. The charging roller 56 is disposed so as to come into contact with the surface layer of the transport belt 51 and to rotate following the rotation of the transport belt 51. The transport belt 51 rotates in the belt transport direction when the transport roller 52 is rotationally driven through timing by a sub-scanning motor described later.

  Further, as a paper discharge unit for discharging the paper 42 recorded by the recording head 34, a separation claw 61 for separating the paper 42 from the conveying belt 51, a paper discharge roller 62, and a spur 63 that is a paper discharge roller. And a paper discharge tray 3 below the paper discharge roller 62.

  A duplex unit 71 is detachably mounted on the back surface of the apparatus body 1. The duplex unit 71 takes in the paper 42 returned by the reverse rotation of the conveyance belt 51, reverses it, and feeds it again between the counter roller 46 and the conveyance belt 51. The upper surface of the duplex unit 71 is a manual feed tray 72.

  Further, a maintenance / recovery mechanism 81 for maintaining and recovering the nozzle state of the recording head 34 is disposed in the non-printing area on one side of the carriage 33 in the scanning direction. The maintenance / recovery mechanism 81 includes cap members (hereinafter referred to as “caps”) 82a and 82b (hereinafter referred to as “caps 82” when not distinguished from each other) for capping the nozzle surfaces of the recording head 34, and nozzle surfaces. A wiper member (wiper blade) 83 for wiping the ink, an empty discharge receiver 84 for receiving liquid droplets when performing an empty discharge for discharging liquid droplets that do not contribute to recording in order to discharge thickened ink, and the carriage 33 A carriage lock 87 and the like. A waste liquid tank 100 for storing waste liquid generated by the maintenance recovery operation is mounted on the lower side of the head maintenance recovery mechanism 81 in a replaceable manner with respect to the apparatus main body.

  Further, in the non-printing area on the other side of the carriage 33 in the scanning direction, there is an empty space for receiving liquid droplets when performing empty discharge for discharging liquid droplets that do not contribute to recording in order to discharge the recording liquid thickened during recording or the like. A discharge receiver 88 is disposed, and the idle discharge receiver 88 includes an opening 89 along the nozzle row direction of the recording head 34.

  In this image forming apparatus configured as described above, the sheets 42 are separated and fed one by one from the sheet feed tray 2, and the sheet 42 fed substantially vertically upward is guided by the guide 45, and includes the transport belt 51 and the counter. It is sandwiched between the rollers 46 and conveyed, and the leading end is guided by the conveying guide 37 and pressed against the conveying belt 51 by the leading end pressing roller 49, and the conveying direction is changed by approximately 90 °.

  At this time, a positive output and a negative output are alternately repeated with respect to the charging roller 56, that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 51 alternates, that is, in a sub-scanning direction that is a circumferential direction. , Plus and minus are alternately charged in a band shape with a predetermined width. When the paper 42 is fed onto the conveyance belt 51 charged alternately with plus and minus, the paper 42 is attracted to the conveyance belt 51, and the paper 42 is conveyed in the sub-scanning direction by the circular movement of the conveyance belt 51.

  Therefore, by driving the recording head 34 according to the image signal while moving the carriage 33, ink droplets are ejected onto the stopped paper 42 to record one line, and after the paper 42 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 42 has reached the recording area, the recording operation is finished and the paper 42 is discharged onto the paper discharge tray 3.

  When performing the maintenance and recovery of the nozzles of the recording head 34, the nozzle 33 performs the suction from the nozzles by moving the carriage 33 to a position facing the maintenance and recovery mechanism 81 which is the home position and performing capping by the cap member 82. By performing a maintenance and recovery operation such as idle ejection for ejecting droplets that do not contribute to image formation, image formation by stable droplet ejection can be performed.

  Next, an example of the head tank 35 will be described with reference to FIGS. 3 is a schematic top view for one head of the head tank, and FIG. 4 is a schematic front view for one head of the head tank.

  The head tank 35 has a tank case 201 that forms an ink containing portion 202 that is open at one side for holding ink. The opening of the tank case 201 is sealed with a flexible film-like member 203, The film-like member 203 is constantly urged outward by a spring 204 as an elastic member disposed in the tank case 201. As a result, an outward biasing force is applied to the film-like member 203 of the tank case 201 by the spring 204, so that a negative pressure is generated as the ink remaining amount in the tank case 201 decreases.

  Further, on the outside of the tank case 201, a detection filler 205, which is a displacement member supported at one end by a support shaft 206 so as to be swingable and biased toward the tank case 201, is bonded to the film-like member 203. Etc. are fixed.

  As a result, the detection filler 205 is displaced in conjunction with the movement of the film-like member 203, so that the head tank 35 is detected by detecting the displacement amount of the detection filler 205 by the detection sensor 301 comprising an optical sensor arranged on the apparatus main body side. The remaining ink amount can be detected.

  In addition, a supply port 209 for supplying ink from the ink cartridge 10 is connected to the supply tube 36 at the upper part of the tank case 201. In addition, an air release mechanism 207 that opens the inside of the head tank 35 to the atmosphere is provided on the side of the tank case 201.

  The atmosphere release mechanism 207 includes a valve body 207b that opens and closes an atmosphere release path 207a communicating with the inside of the head tank 35, a spring 207c that biases the valve body 207b to a closed state, and the like. The valve body 207b is pushed by the atmospheric release drive pin member 302, which is a means, and the valve is opened, and the head tank 35 is opened to the atmosphere (a state communicating with the atmosphere).

  Electrode pins 208a and 208b for detecting the remaining amount of ink in the head tank 35 are attached. Since the ink has electrical conductivity, when the ink reaches the electrode pins 208a and 208b, a current flows between the electrode pins 208a and 208b, and the resistance value of the two changes. That is, it can be detected that the air amount in the head tank 35 has become a predetermined amount or more, or that the remaining amount of liquid in the head tank 35 has become a predetermined amount or less.

  Next, an ink supply / discharge system of the image forming apparatus will be described with reference to FIG. Here, in order to simplify the illustration, only one ink supply system from the ink cartridge to the head tank is shown, but an ink supply system is provided for each color.

  First, ink is supplied from the ink cartridge (main tank) 10 to the head tank 35 through a supply tube 36 by a liquid feed pump 241 which is a liquid feed means provided for each color in the supply pump unit 24. The liquid feed pump 241 is a reversible pump configured by a tube pump or the like, and includes a liquid feed operation for supplying ink from the ink cartridge 10 to the head tank 35 and a reverse feed for returning ink from the head tank 35 to the ink cartridge 10. It is possible to perform actions.

  The maintenance / recovery mechanism 81 has the suction cap 82a for capping the nozzle surface of the recording head 34 and the suction pump 812 connected to the suction cap 82a as described above, and the suction pump 812 is capped with the cap 82a. By driving the, the ink in the head tank 35 can be sucked by sucking ink from the nozzles via the suction tube 811. The sucked waste ink is discharged to the waste liquid tank 100.

  An air release drive pin member 302 that is an air release drive means (pressing member) that opens and closes the air release mechanism 207 of the head tank 35 is disposed on the apparatus main body side, and the air release drive pin member 302 is operated. The atmospheric release mechanism 207 can be opened. Further, a sensor 301 including an optical sensor for detecting the detection filler 205 of the head tank 35 is provided on the apparatus main body side.

  Here, the four liquid feed pumps 241, the suction pumps 812, and the atmosphere release drive pin member 302 of each color have the drive force of the first drive motor 101, which is the first drive source, as the second drive source (both the switching drive source). The first drive motor 101 is controlled and driven by the control unit 500. The drive switching mechanism 400 is selectively driven by the second drive motor 102.

Next, an example of a tube pump used as the liquid feed pump 241 and the suction pump 812 will be described with reference to FIG.
The tube pump 901 can transfer the liquid in the tube 902 by crushing the tube 902 with an eccentric pressing roller 903 that rotates in the direction of the arrow.

  When this tube pump 901 is used for the liquid feed pump 241, the pressure roller 903 is rotated in both directions indicated by the arrows, so that the liquid is fed from the ink cartridge 10 to the head tank 35 and the reverse feed from the head tank 35 to the ink cartridge 10. It can be performed. Further, when used in the suction pump 812, suction can be performed by rotating the pressing roller 903 in one direction.

Next, an outline of the control unit of the image forming apparatus will be described with reference to FIG. In addition, the figure is a block explanatory drawing of the control part.
The control unit 500 includes a CPU 501 that controls the entire apparatus that also functions as a motor drive control unit in the present invention, a ROM 502 that stores programs executed by the CPU 501 and other fixed data, and a RAM 503 that temporarily stores image data and the like. A rewritable non-volatile memory 504 for holding data while the power of the apparatus is cut off, image processing for performing various signal processing and rearrangement on image data, and other inputs for controlling the entire apparatus. And an ASIC 505 for processing the output signal.

  Further, a print control unit 508 including a data transfer unit for driving and controlling the recording head 34 and a driving signal generating unit, a head driver (driver IC) 509 for driving the recording head 34 provided on the carriage 33 side, A main scanning motor 554 that moves and scans the carriage 33, a sub-scanning motor 555 that moves the conveyor belt 51 around, an AC bias supply unit 511 that supplies an AC bias to the charging roller 56, the first drive motor 101, and the drive switching mechanism 400. A motor drive unit 512 for driving the second drive motor 102 is provided.

  The control unit 500 is connected to an operation panel 514 for inputting and displaying information necessary for the apparatus.

  The control unit 500 has an I / F 506 for transmitting and receiving data and signals to and from the host side, an information processing device such as a personal computer, an image reading device such as an image scanner, an imaging device such as a digital camera, and the like. From the host 600 side via the cable or network via the I / F 506.

  The CPU 501 of the control unit 500 reads and analyzes the print data in the reception buffer included in the I / F 506, performs necessary image processing, data rearrangement processing, and the like in the ASIC 505, and prints the image data. The data is transferred from the unit 508 to the head driver 509. Note that generation of dot pattern data for image output is performed by the printer driver 601 on the host 600 side.

  The print control unit 508 transfers the above-described image data as serial data, and outputs a transfer clock, a latch signal, a control signal, and the like necessary for transferring the image data and confirming the transfer to the head driver 509. Including a D / A converter for D / A converting D / A conversion of drive pulse pattern data stored in the ROM, a voltage signal amplifier, a current amplifier, and the like, and a drive signal or a plurality of drive pulses Is output to the head driver 509.

  The head driver 509 selectively selects a drive pulse that constitutes a drive signal provided from the print control unit 508 based on image data corresponding to one line of the print head 34 that is input serially, and drops droplets on the print head 34. The recording head 34 is driven by applying it to a driving element (for example, a piezoelectric element) that generates energy to be discharged. At this time, by selecting a driving pulse constituting the driving signal, for example, dots having different sizes such as a large droplet, a medium droplet, and a small droplet can be sorted.

  The I / O unit 513 acquires information from various sensor groups 515 mounted on the apparatus, extracts information necessary for controlling the printer, and print control unit 508, motor control unit 510, AC bias supply unit Used to control 511. The sensor group 515 includes an optical sensor for detecting the position of the paper, a thermistor for monitoring the temperature and humidity in the machine, a sensor for monitoring the voltage of the charging belt, an interlock switch for detecting opening and closing of the cover, and the like. The I / O unit 513 can process various sensor information. Signals such as the detection sensor 301 for detecting the detection filler 205 of the head tank 35 and the detection electrode pins 208a and 208b are also input to the sensor group 515 input to the I / O unit 513.

  In addition, the control unit 500 includes time measuring means 520 that measures time.

  Next, a drive switching mechanism according to an embodiment of the present invention will be described with reference to FIGS. 8 is a schematic explanatory view for explaining the drive switching mechanism of the embodiment, FIG. 9 is a perspective explanatory view of a specific configuration of the drive switching mechanism, and FIG. 10 is a perspective explanatory view with the cam portion removed, FIG. 11 is an explanatory perspective view of the cam and the slider member. In FIG. 8, a broken line P in the figure indicates that the two gears are always engaged, and a virtual line Q indicates that the two gears are engaged and separated (the same applies to the following drawings). is there.).

  The drive shaft 104 rotated by the first drive motor 101 is provided with gears 104A and 104B.

  On the other hand, the second drive motor 102 of the drive switching mechanism 400 is composed of a stepping motor. The cam shaft 131 rotated by the second drive motor 102 is provided with cams 103A and 103B (referred to as “cam 103” when not distinguished). Cam grooves 107 are formed in the cams 103A and 103B.

  And it has the engaging part 105a engaged with each cam groove 107 of cam 103A, 103B, and is moved to the thrust direction (the axial direction of the cam shaft 131) shown by the arrow in conjunction with the rotation of the cams 103A, 103B. Slider members 105 </ b> A to 105 </ b> D (referred to as “slider member 105” when not distinguished) are provided.

  In FIG. 7, for the sake of clarity, the engaging portion 105a of the slider member 105 and the cam groove 107 of the cam 103 are shown apart from each other, but are in slidable contact as described above (the following drawings). But the same shall apply.)

  A first switching gear 106A that meshes with a gear 104A that is rotated by the first drive motor 101 is rotatably provided on the slider member 105A. The slider member 105B is rotatably provided with a switching gear 106B that meshes with the gear 104B that is rotated by the first drive motor 101.

  The slider member 105C is rotatably provided with a switching gear 106C that meshes with a gear 104A that is rotated by the first drive motor 101. The slider member 105D is rotatably provided with a switching gear 106C that meshes with a gear 104B that is rotated by the first drive motor 101.

  Then, the switching gear 106A does not mesh with any position that meshes with either the drive gear 112a of the first color liquid feed pump 241 or the drive gear 112b of the second color liquid feed pump 241 due to the movement of the slider member 105A. It is moved between positions (positions that are separated).

  The position of the switching gear 106B that does not mesh with either the position of the driving gear 112c of the third color liquid feeding pump 241 or the position of the driving gear 112d of the fourth color liquid feeding pump 241 due to the movement of the slider member 105B ( The position is moved to (separated position).

  The switching gear 106C is moved between a position where it engages with the drive gear 113 of the suction pump 812 of the maintenance / recovery mechanism 81 and a position where it is separated by the movement of the slider member 105C.

  The switching gear 106D is moved between a position that engages with the drive gear 114 that moves (advances and retreats) the air release drive pin member 302 and a position that moves away by the movement of the slider member 105D.

  In this embodiment, the switching gears 106A and 106B are the first switching gear, the switching gear 106C is the second switching gear, and the switching gear 106D is the third switching gear. Further, the first to fourth colors supplied from the four liquid feeding pumps 241 are, for example, any one of the above-described black, cyan, magenta, and yellow.

  Further, in the specific configuration shown in FIGS. 9 to 11, the driving force of the first drive motor 101 is transmitted by the motor gear 141, the gear 142 rotatably mounted on the support shaft 152, and the gear 143 fixed to the drive shaft 104. Then, it is transmitted to the drive shaft 104. In addition, the driving force of the second drive motor 102 which is a switching drive source is transmitted to the cam shaft 131 through the motor gear 132, the gear 133 and the gear 134 fixed to the cam shaft 131. The slider member 105A and the switching gear 106A, the slider member 105B, and the switching gear 106B are supported by the support shaft 151 so as to be movable. The slider member 105C and the switching gear 106C, the slider member 105D and the switching gear 106D are supported by the support shaft 152 so as to be movable.

  Since it comprised in this way, a driving force is transmitted to 1st switching gear 106A, 106B, 2nd switching gear 106C, and 3rd switching gear 106D via gear 104A, 104B by driving the 1st drive motor 101. Thus, each switching gear 106A to 106D rotates.

  Here, by rotating the second drive motor 102 to rotate the cams 103A and 103B, the slider members 105A to 105D move in the direction indicated by the arrows, and the first switching gears 106A and 106B, the second switching gear 106C, The three switching gear 106D also moves in the direction indicated by the arrow.

  At this time, when the first switching gear 106A is moved to a position where it engages with the drive gear 112a, the first color liquid feed pump 241 is driven. Similarly, when the first switching gear 106A is moved to a position where it engages with the drive gear 112b, the second color liquid feed pump 241 is driven.

  Further, by moving the slider member 105B in the direction indicated by the arrow, the third color liquid feeding pump 241 is driven when the first switching gear 106B is moved to a position where the first switching gear 106B is engaged with the drive gear 112c. Similarly, when the first switching gear 106B is moved to a position where it meshes with the drive gear 112d, the fourth color liquid feed pump 241 is driven.

  Further, when the second switching gear 106C is moved to a position where it is engaged with the drive gear 113 by moving the slider member 105C in the direction of the arrow, the suction pump 812 of the maintenance / recovery mechanism 81 is driven.

  Further, when the third switching gear 106D is moved to a position where it is meshed with the drive gear 114 by moving the slider member 105D in the direction indicated by the arrow, the atmospheric release drive pin member 302 is driven forward and backward.

  In this case, since the driving force can be transmitted to each liquid feed pump 241 regardless of the rotation direction of the first drive motor 101, the liquid feed pump 241 is fed in the liquid feed direction (forward rotation driving) as described above. And it can be driven in any direction of the reverse feed direction (reverse direction).

  In addition, by changing the phase of the cam groove 107 of the cams 103A and 103B, or by connecting a plurality of slider members 105 to the cams 103A and 103B in different phases, each of the switching gears 106A to 106D is rotated while the cams 103A and 103B rotate. It is also possible to sequentially switch, or conversely, simultaneously connect to a plurality of drive gears.

  Further, by using a plurality of (two in this example) cams, the distance of the switching gear to be moved by one cam can be shortened, and the cam diameter can be reduced. Moreover, even if five or more switching gears are arranged in the thrust direction (axial direction), it is possible to deal with without changing the size other than the thrust direction.

  As described above, the first driving source that drives the plurality of liquid feeding pumps, and the drive switching mechanism that selectively transmits the driving force of the first driving source to the plurality of liquid feeding pumps, The second drive source, the cam rotated by the second drive source, the slider member moved in the thrust direction in conjunction with the rotation of the cam, and the driving force of the first drive source are transmitted. A first switching gear that is moved between a position that meshes with a drive gear of the liquid feeding pump and a position that is separated from the driving gear, and the first switching gear is moved to selectively select the plurality of liquid feeding pumps. Since the driving force of one driving source is transmitted and the driving source of the pump and the power of the drive switching mechanism are separated, a plurality of pumps and the like can be driven with a small degree of freedom.

  In other words, by using the drive switching mechanism in the present invention, the forward rotation and the reverse rotation of the first drive source can be transmitted independently from the drive gears of other pumps and units. Without being received, it can be freely operated in the same manner as the configuration driven by a single drive source.

  Next, an example of drive control of the second drive source of the drive switching mechanism in the present invention will be described with reference to FIGS. FIG. 13 is a schematic explanatory view for explaining the drive switching mechanism in this example, FIG. 13 is an explanatory view for explaining the cam position detecting mechanism of the drive switching mechanism, and FIG. 14 shows the drive transmission target of the embodiment. It is explanatory drawing with which it uses for description of the relationship between a cam position (cam angle), the number of step pulses from the home position of a 2nd drive source, and the detection signal of a switching sensor.

  Here, as shown in FIG. 12, the drive switching mechanism 400 switches the driving gears 112a and 112b by the first switching gear 106A, and switches the driving gears 112c and 112d by the first switching gear 106B. . Further, it is assumed that the drive gear 112a is for black, the drive gear 112b is for cyan, the drive gear 112c is for magenta, and the drive gear 112d is for driving yellow.

  A cam position detection mechanism (means) 401 for detecting the cam position is provided. In the cam position detection mechanism 401, the cam 103 is provided with a sensor flag 161 which is a predetermined position detected portion for detecting the home position of the cam 103 and a position rotated by a predetermined angle from the home position. The sensor flag 161 is a convex portion formed continuously from the home position to a predetermined position (in this example, 180 °) on the outer periphery of the cam 103.

  And the switching sensor 162 as a detection means which detects this sensor flag 161 is arrange | positioned. The switching sensor 162 is composed of, for example, a transmissive photosensor, and outputs a signal in the first state (turns on) while the sensor flag 161 is detected, and outputs a signal when the sensor flag 161 is not detected. 2 state (OFF state) signal is output. The switching sensor 162 may be a mechanical ON / OFF sensor instead of the optical sensor.

  Therefore, when the cam 103 rotates from the home position (which is set to 0 °), a signal indicating the ON state is output from the switching sensor 162, and when the cam 103 rotates 180 °, the state transits from the ON state to the OFF state. Thus, a signal in the OFF state is continuously output until the cam 103 returns to the home position, and a signal for transitioning from the OFF state to the ON state is output when the cam 103 returns to the home position.

  The home position of the cam 103 can be detected when the output signal of the switching sensor 162 transitions from the OFF state to the ON state. Further, it can be detected that the cam 103 has rotated from the home position to the predetermined position when the output signal of the switching sensor 162 transitions from the ON state to the OFF state.

  In this configuration, as shown in FIG. 14A, when the home position of the cam 103 is 0 ° and the rotation angle of the cam 103 is 0 ° (360 °), the drive gear 112c for magenta and the first drive The gear 106B is engaged and the drive is transmitted. When the rotation angle of the cam 103 is 90 °, the drive gear 112a for black and the first drive gear 106A are engaged and the drive is transmitted, and the rotation angle of the cam 103 is 180 °. The drive gear 112b for cyan and the first drive gear 106A mesh with each other and drive is transmitted, and when the rotation angle of the cam 103 is 270 °, the drive gear 112d for yellow and the first drive gear 106B mesh with each other. Drive is transmitted.

  At this time, assuming that the rotation accuracy of the second drive motor 102 configured by a stepping motor that rotates the cam 103 is set to rotate 1 ° by one pulse, as shown in FIG. When in the home position, the count value from the home position of the step pulse (stepping pulse) given to the second drive motor 102 is “0”.

  From this state, by applying 90 step pulses to the second drive motor 102, the cam 103 rotates, the cam 103 rotates 90 ° from the home position, and the black drive gear 112a and the first drive gear 106A move. The drive is transmitted by meshing. Similarly, the cyan drive gear 112b and the first drive gear 106A mesh with each other by giving 180 step pulses, and the drive is transmitted. By giving 270 step pulses, the magenta drive gear 112c and the first drive gear 112c are transmitted. The drive gear 106B meshes to transmit drive. By giving 270 step pulses, the yellow drive gear 112d and the first drive gear 106B are engaged with each other, and the drive is transmitted.

  Here, for comparison, a comparative example will be described with reference to FIG.

  In this comparative example, a sensor flag 163 as a convex portion is provided at a portion corresponding to the home position of the cam 103, and when the sensor flag 163 is detected by the switching sensor 162 as shown in FIG. When the home position of the cam 103 is detected, the count value of the step pulse given to the second drive motor 102 is reset, and recounting is started.

  That is, in the comparative example, by resetting the count value of the step pulse at the home position, the previous error is reset. Therefore, when the drive transmission destination is sequentially switched from M (magenta) → K (black) → C (cyan) → Y (yellow), the physical rotation error accumulated for some reason at the time of drive switching is As the switching is repeated, it becomes larger, and there is a risk of switching abnormality, for example, gear meshing abnormality, motor step-out, and transmission destination error.

  More specifically, suppose that the switchable angle range to the position of each color is an angle ± 10 ° from the home position, the home position moves from M (magenta) to K (black), and then Y (yellow). ) Consider the case of moving to the position. Originally, the cam 103 is rotated by 90 ° by driving 90 pulses from the home position to the K position.

  However, it is assumed that a step-out occurs due to accidental overload or the like, and the rotation is 85 ° which is smaller than 90 °. At that time, it is within 90 ° ± 10 ° from the home position and operates without any problem (the driving force is transmitted).

  Then, Y (yellow) is selected as it is, and 180 pulses (270 pulses from the home position) are added from the K (black) position. If normal, the cam 103 rotates 180 °. However, again, if a step-out occurs and the cam 103 can only rotate by 170 °, Y (yellow) is originally 270 ° ± 10 ° (range 260 ° to 280 °) from the home position. If there is no problem in switching, the rotation error is accumulated as 75 ° + 170 ° = 245 °, and as a result, switching abnormality (normal drive transmission cannot be performed) will occur.

  Here, since the second drive motor 102 is a stepping motor, the rotation is not constantly fed back by an encoder or the like, so that the step-out cannot be detected, and the home position is set once again to prevent error accumulation. If it is moved back to the Y (yellow) position after returning, the switching time is wasted.

  Therefore, in this embodiment, as shown in FIG. 14B, the cam 103 indicates that the cam 103 has reached a position rotated by 180 °, which is a predetermined position from the home position (in this example, the cyan position). Detected by the switching sensor 162 of the position detection mechanism 401, the count value of the step pulse given to the second drive motor 102 is corrected when this predetermined position is detected.

  For correction of the count value, for example, the count value itself may be reset and recounting may be started from 180 °, or the count value may be forcibly replaced with a count value corresponding to a predetermined position. Thus, the count may be continued.

  By doing so, it is possible to prevent occurrence of switching abnormality due to accumulation of errors.

  Next, another example of drive control of the second drive source of the drive switching mechanism in the present invention will be described with reference to FIG. FIG. 16 is an explanatory diagram for explaining the relationship among the drive transmission target, the cam position (cam angle), the number of step pulses from the home position of the second drive source, and the detection signal of the switching sensor.

  Here, as described with reference to FIG. 8, the drive gears 112a to 112d corresponding to the four liquid feed pumps, the drive gear 113 of the maintenance / recovery mechanism, and the drive gear 114 of the atmospheric release drive pin member are connected to the cam 103A. , 103B to selectively transmit the drive.

  Then, as shown in FIG. 16, when the cam 103 is rotated at a predetermined position, for example, 180 ° from the home position, the count value of the step pulse for the second drive motor 102 is reset or the count value corresponding to 180 ° is reset. Forced replacement is performed.

  By doing so, it is possible to prevent the occurrence of switching abnormality due to accumulation of errors, as described above.

  In each of the above embodiments, the predetermined position detected portion in the cam position detection mechanism is described as an example formed by a convex portion continuous from the home position, but the present invention is not limited to this, and the predetermined position A configuration may be provided in which a detected part different from the home position is provided. However, the detection of the home position and the predetermined position is simplified and the control is simplified by configuring the detected portion with a continuous convex portion as in the above embodiment.

  In the present application, “paper” is not limited to paper, but includes OHP, cloth, glass, a substrate, and the like, and means that ink droplets, other liquids, and the like can adhere to the recording medium, recording medium, and recording medium. This includes media, recording paper, and recording paper. In addition, image formation, recording, printing, printing, and printing are all synonymous.

  The “image forming apparatus” means an apparatus that forms an image by discharging liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc. “Formation” means not only giving an image having a meaning such as a character or a figure to a medium but also giving an image having no meaning such as a pattern to the medium (simply causing a droplet to land on the medium). ) Also means.

  The “ink” is not limited to an ink unless otherwise specified, but includes any liquid that can form an image, such as a recording liquid, a fixing processing liquid, or a liquid. Used generically, for example, includes DNA samples, resists, pattern materials, resins, and the like.

  In addition, the “image” is not limited to a planar image, and includes an image given to a three-dimensionally formed image and an image formed by three-dimensionally modeling a solid itself.

  Further, the image forming apparatus includes both a serial type image forming apparatus and a line type image forming apparatus, unless otherwise limited.

10 Ink cartridge (main tank)
33 Carriage 34, 34a, 34b Recording head (liquid ejection head)
35 Head tank 36 Supply tube 81 Maintenance recovery mechanism 101 First drive motor (first drive source)
102 Second drive motor (second drive source: switching drive source)
103, 103A, 103B Cam 105 Slider member 106, 106A to 106D Switching gear 107 Cam groove 108 Cam 109 Spring (elastic member)
111 Liquid feed pump drive gear 112, 112a to 112d Liquid feed pump drive gear 113 Suction pump drive gear 114 Air release drive pin member drive gear 151 Sensor flag (detected portion)
152 switching sensor 241 liquid feed pump 400 drive switching mechanism 500 control unit 600 host (information processing apparatus)

Claims (4)

A recording head that ejects different types of droplets;
A plurality of head tanks for supplying liquid to the recording head;
A plurality of replaceable main tanks for storing liquid to be supplied to the recording head;
A plurality of liquid feed pumps for feeding the liquid from each main tank to the head tank, and for feeding back the liquid from the head tank to the main tank;
A first drive source for driving the plurality of liquid feed pumps;
A drive switching mechanism that selectively transmits the driving force of the first drive source to the plurality of liquid feeding pumps,
The drive switching mechanism is
A second drive source comprising a stepping motor;
A cam rotated by the second drive source;
A slider member that moves in a thrust direction in conjunction with rotation of the cam;
A switching gear to which the driving force of the first driving source is transmitted and moved by the slider member between a position engaging with a driving gear of the plurality of liquid feeding pumps and a position separating from the position.
By moving the switching gear, the driving force of the first driving source is selectively transmitted to the plurality of liquid feeding pumps,
Motor drive control means for driving and controlling the second drive source;
The cam is provided with a predetermined position detected portion for detecting a predetermined position obtained by rotating the cam by a predetermined angle from a predetermined home position,
Having detection means for detecting the predetermined position detected portion;
The motor drive control means corrects the count value of the step number for the second drive source to a count value of the step number corresponding to the predetermined position when the detection means detects the predetermined position detected portion. An image forming apparatus. On the outer periphery of the cam, there is a detected part continuously formed from the home position to the predetermined position,
The detection means outputs a first state signal while detecting the detected portion, and outputs a second state signal when the detected portion is no longer detected.
The image forming apparatus according to claim 1, wherein the motor control unit corrects the count value of the step number when the output signal of the detection unit transitions from the first state to the second state. A suction pump connected to a cap member for capping the nozzle surface of the recording head;
The drive switching mechanism has a switching gear to which the driving force of the first driving source is transmitted and which is moved between a position engaging with the driving gear of the suction pump and a position separating from the position by the slider member. The image forming apparatus according to claim 1, wherein: The head tank has an openable / closable atmosphere opening mechanism that opens the interior to the atmosphere,
The apparatus main body side is provided with an atmospheric release driving means for driving the atmospheric release mechanism,
The drive switching mechanism has a switching gear to which the driving force of the first driving source is transmitted and which is moved by the slider member between a position engaging with the driving gear of the atmosphere release driving means and a position separating from the position. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.

Images