Patent Publication Number: US-9421786-B2

Title: Damper device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a 371 application of an international PCT application serial no. PCT/JP2013/079416, filed on Oct. 30, 2013, which claims the priority benefit of Japan application no. 2012-245857, filed on Nov. 7, 2012. The entirety of each of the above-mentioned patent applications is hereby incorporated by reference herein and made a part of this specification. 
     TECHNICAL FIELD 
     The present invention relates to a damper device that is provided in an inkjet printer including a recording head that discharges ink and a tank that supplies the ink, and the damper device is configured to supply the ink supplied from the tank to the recording head while suppressing pressure fluctuation. 
     BACKGROUND ART 
     In a conventional damper device, a valve unit is known (see Patent Document 1). The valve unit is formed to includes a pressure chamber as a head-side chamber communicating with a recording head, an ink supplying chamber as a tank-side chamber communicating with an ink cartridge as a tank, and an ink supplying hole as a communicating passage communicating the pressure chamber and the ink supplying chamber, and the valve unit further includes a plate-shaped member as a valve for opening or closing the ink supplying hole, a sealing spring as a spring biasing the plate-shaped member in a direction to close the ink supplying hole by the plate-shaped member, a pressure receiving plate as a pressure receiving unit that receives air pressure, and changes a volume of the pressure chamber according to a change in its own position, a rod member as a force transmitting unit that is arranged between the plate-shaped member and the pressure receiving plate, and transmits force received from one of the plate-shaped member and the pressure receiving plate to the other thereof, and a flexible film member that extends in a direction that is vertical to a direction along which the plate-shaped member opens or closes the ink supplying hole, and supports the pressure receiving plate so that a position of the pressure receiving plate is changeable. 
     PRIOR ART DOCUMENT 
     Patent Document 
     Patent Document 1: JP 3606282 B 
     SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
     However, in a conventional damper device, since the pressure receiving unit receives force necessary for the valve to open the communicating passage by the air pressure, an area of the pressure receiving unit in a direction that is vertical to the direction along which the valve opens or closes the communicating passage must be made large. Further, in the conventional damper device, a width in the direction that is vertical to the direction along which the valve opens or closes the communicating passage must be made large in a deformable portion within the flexible film member, which is supporting the pressure receiving unit to obtain the change in the position of the pressure receiving unit needed for the valve to open the communicating passage. Accordingly, the conventional damper device has a problem that its size in the direction that is vertical to the direction along which the valve opens or closes the communicating passage becomes large. 
     Thus, the present invention aims to provide a damper device that can make the size in the direction that is vertical to the direction along which the valve opens or closes the communicating passage smaller than in the conventional configurations. 
     Solutions to the Problem 
     A damper device of the present invention is provided in an inkjet printer including a recording head that discharges ink, and a tank that supplies the ink, is configured to supply the ink supplied from the tank to the recording head while suppressing pressure fluctuation, and is characteristic in including: a head-side chamber communicating with the recording head; a tank-side chamber communicating with the tank; a communicating passage that communicates the head-side chamber and the tank-side chamber; a valve configured to open or close the communicating passage; a biasing member that biases the valve in a direction along which the valve closes the communicating passage; a pressure receiving unit that receives air pressure, and changes a volume of the head-side chamber according to a change in a position of itself; a force transmitting unit arranged between the valve and the pressure receiving unit, and configured to transmit force received from one of the valve and the pressure receiving unit to the other thereof; and a bellows unit that supports the pressure receiving unit so that the position of the pressure receiving unit is changeable. 
     According to this configuration, the damper device of the present invention does not change the position of the pressure receiving unit by deformation of the flexible film member itself as in the conventional configuration, but changes the position of the pressure receiving unit by folding deformation of the bellows unit; thus, the conventional flexible film member that extends in the direction that is vertical to the direction along which the valve opens or closes the communicating passage and supports the pressure receiving unit so that the position of the pressure receiving unit is changeable is no longer necessary. Accordingly, the damper device of the present invention can make its size in the direction that is vertical to the direction along which the valve opens or closes the communicating passage smaller than the conventional configuration. 
     Further, in the damper device of the present invention, the bellows unit may include a plurality of plates, and a bendable connecting unit that connects the plates, and the plates and the bendable connecting unit may be formed as one component made of synthetic resin. 
     According to this configuration, in the damper device of the present invention, the plates and the bendable connecting unit can be manufactured by integral formation of the synthetic resin. Accordingly, the damper device of the present invention can reduce manufacturing cost, for example. 
     Further, in the damper device of the present invention, the pressure receiving unit may be supported rotatably. 
     According to this configuration, in the damper device of the present invention, in the situation where the valve transmits force to the pressure receiving unit via the force transmitting unit at a farther side from a rotation center of the pressure receiving unit, since the moving amount of the valve relative to decreasing amount of the ink in the head-side chamber can be increased compared to the configuration in which an entirety of the pressure receiving unit moves in the direction along which the valve opens or closes the communicating passage, pressure fluctuation of the ink in the head-side chamber can be made less. Further, in the damper device of the present invention, in the situation where the valve transmits force to the pressure receiving unit via the force transmitting unit in a vicinity of the rotation center of the pressure receiving unit, even if the size of the pressure receiving unit is made smaller in the direction that is vertical to the direction along which the valve opens or closes the communicating passage, the force needed for the valve to open the communicating passage can be obtained by the pressure receiving unit by air pressure, as compared to the configuration in which the entirety of the pressure receiving unit moves in the direction along which the valve opens or closes the communicating passage. 
     Further, in the damper device of the present invention, the pressure receiving unit and a supporting unit rotatably supporting the pressure receiving unit may be formed as one component made of synthetic resin. 
     According to this configuration, in the damper device of the present invention, the pressure receiving unit and the supporting unit can be manufactured by the integral formation of the synthetic resin. Accordingly, the damper device of the present invention can reduce manufacturing cost, for example. 
     Effects of the Invention 
     The damper device of the present invention can make its size in the direction that is vertical to the direction along which the valve opens or closes the communicating passage smaller than the conventional configuration. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective diagram of an inkjet printer according to a first embodiment of the present invention. 
         FIG. 2  is a schematic diagram of an ink supplying system of the inkjet printer shown in  FIG. 1 . 
         FIG. 3  is a front side cross sectional diagram of a damper device shown in  FIG. 2  in the situation where a valve is closing a communicating passage. 
         FIG. 4  is a front side diagram of the damper device shown in  FIG. 2  in the situation where the valve is closing the communicating passage. 
         FIG. 5  is a planar diagram of the damper device shown in  FIG. 2  in the situation where the valve is closing the communicating passage. 
         FIG. 6  is a cross sectional diagram of a part of a bellows unit shown in  FIG. 3 . 
         FIG. 7  is an expanded diagram of the bellows unit shown in  FIG. 3 . 
         FIG. 8  is a front side cross sectional diagram of the damper device shown in  FIG. 2  in the situation where the valve is opening the communicating passage. 
         FIG. 9  is a cross sectional diagram of a part of the bellows unit shown in  FIG. 3 , and is a diagram showing a different example from the example shown in  FIG. 6 . 
         FIG. 10  is a front side cross sectional diagram of the damper device shown in  FIG. 2  in the situation where the valve is closing the communicating passage, and is a diagram showing a different example from the example shown in  FIG. 3 . 
         FIG. 11  is a front side cross sectional diagram of the damper device shown in  FIG. 2  in the situation where the valve is closing the communicating passage, and is a diagram showing a different example from the examples shown in  FIG. 3  and  FIG. 10 . 
         FIG. 12  is a front side cross sectional diagram of a damper device of an inkjet printer according to a second embodiment of the present invention in the situation where a valve is closing a communicating passage. 
         FIG. 13  is a front side diagram of the damper device shown in  FIG. 12 . 
         FIG. 14  is a planar diagram of the damper device shown in  FIG. 12 . 
         FIG. 15  is a front side cross sectional diagram of the damper device shown in  FIG. 12  in the situation where the valve is opening the communicating passage. 
         FIG. 16  is a front side cross sectional diagram of the damper device of the inkjet printer according to the second embodiment of the present invention in the situation where the valve is closing the communicating passage, and is a diagram showing a different example from the example shown in  FIG. 12 . 
         FIG. 17  is a front side cross sectional diagram of the damper device of the inkjet printer according to the second embodiment of the present invention in the situation where the valve is closing the communicating passage, and is a diagram showing a different example from the examples shown in  FIG. 12  and  FIG. 16 . 
         FIG. 18  is a front side cross sectional diagram of the damper device of the inkjet printer according to the second embodiment of the present invention in the situation where the valve is closing the communicating passage, and is a diagram showing a different example from the examples shown in  FIG. 12 ,  FIG. 16 , and  FIG. 17 . 
     
    
    
     EMBODIMENTS OF THE INVENTION 
     Hereinbelow, embodiments of the present invention will be described with reference to the drawings. 
     First Embodiment 
     Firstly, a configuration of an inkjet printer according to the present embodiment will be described. 
       FIG. 1  is a perspective diagram of an inkjet printer  10  according to the present embodiment. 
     As shown in  FIG. 1 , the inkjet printer  10  includes a main body  11  extending in a main scanning direction shown by an arrow  10   a , a transfer device  12  that transfers recording medium  90  such as paper, and a tank  13  that supplies ink. 
     The main body  11  includes a guide rail  11   a  extending in the main scanning direction shown by the arrow  10   a , and a carriage  11   b  supported on the guide rail  11   a  so as to be movable in the main scanning direction shown by the arrow  10   a.    
     The transfer device  12  is a device that transfers the recording medium  90  in a sub scanning direction shown by an arrow  10   b  relative to a later-described recording head  11   c  of the main body  11 . 
       FIG. 2  is a schematic diagram of an ink supplying system  14  of the inkjet printer  10 . 
     As shown in  FIG. 2 , the ink supplying system  14  includes the recording head  11   c  that discharges ink  10   c  onto the recording medium  90 , the aforementioned tank  13  that supplies the ink  10   c , and a damper device  20  that supplies the ink  10   c  supplied from the tank  13  to the recording head  11   c  while suppressing pressure fluctuation. 
     The recording head  11   c  and the damper device  20  are mounted on a carriage  11   b.    
     The inkjet printer  10  includes the recording head  11   c , the tank  13 , and the damper device  20  at least for each of types of the ink  10   c . The types of the ink  10   c  differ depending on the color type, such as cyan, magenta, yellow, black, and the like. 
     The inkjet printer  10  shown in  FIG. 1  is a device that causes printing by the recording head  11   c  in the main scanning direction to be executed by moving the recording head  11   c  in the main scanning direction using the carriage  11   b  relative to the recording medium  90  that does not move in the main scanning direction shown by the arrow  10   a , and discharging the ink  10   c  from nozzles of the recording head  11   c  to the recording medium  90 . Further, the inkjet printer  10  is a device that changes a position of the recording head  11   c  in the sub scanning direction relative to the recording medium  90  each time the printing in the main scanning direction ends, by transferring the recording medium  90  in the sub scanning direction using the transfer device  12  relative to the recording head  11   c  that does not move in the sub scanning direction shown by the arrow  10   b.    
       FIG. 3  is a front side cross sectional diagram of the damper device  20  in the situation where a valve  23  is closing a communicating passage  20   e.    
     As shown in  FIG. 3 , the damper device  20  includes a head-side chamber  20   a  that communicates with the recording head  11   c , a passage  20   b  configuring a part of a passage communicating the recording head  11   c  and the head-side chamber  20   a , a tank-side chamber  20   c  that communicates with the tank  13 , a passage  20   d  configuring a part of a passage communicating the tank  13  and the tank-side chamber  20   c , and a communicating passage  20   e  that communicates the head-side chamber  20   a  and the tank-side chamber  20   c.    
       FIG. 4  is a front side diagram of the damper device  20  in the situation where the valve  23  is closing the communicating passage  20   e .  FIG. 5  is a planar diagram of the damper device  20  in the situation where the valve  23  is closing the communicating passage  20   e.    
     As shown in  FIG. 3  to  FIG. 5 , the damper device  20  includes a case  21  in which the passage  20   b  and the passage  20   d  are formed, a cover  22  fixed to the case  21 , the valve  23  for opening or closing the communicating passage  20   e , a spring  24  as a biasing member that is fixed to the cover  22  and the valve  23 , and biases the valve  23  in a direction shown by arrow  20   f  along which the valve  23  closes the communicating passage  20   e , an o-ring  25  that is fixed to the case  21  and configured to prevent leakage of the ink  10   c  between the case  21  and the valve  23  in a situation where the valve  23  is closing the communicating passage  20   e , a pressure receiving plate  26  as a pressure receiving unit that receives air pressure, and changes a volume of the head-side chamber  20   a  according to a change in the position of itself, a rod member  27  as a force transmitting unit that is arranged between the valve  23  and the pressure receiving plate  26  and configured to transmit force received from one of the valve  23  and the pressure receiving plate  26  to the other thereof, and a bellows unit  28  that supports the pressure receiving plate  26  so that the position of the pressure receiving plate  26  is changeable. 
     The head-side chamber  20   a  is formed by the case  21 , the pressure receiving plate  26 , and the bellows unit  28 . 
     The tank-side chamber  20   c  is formed by the case  21  and the cover  22 . 
     The communicating passage  20   e  is formed by the case  21  and the rod member  27 . 
     The case  21  has a hole  21   a  through which the rod member  27  is to be inserted. The case  21  is formed by synthetic resin such as polyethylene. 
     The cover  22  is formed by synthetic resin such as polyethylene. The cover  22  is fixed to the case  21  by an adhesive. 
     The valve  23  is formed together with the rod member  27  as one component made of synthetic resin such as polyethylene. 
     The pressure receiving plate  26  is formed by synthetic resin such as polyethylene. The pressure receiving plate  26  does not have flexibility. 
       FIG. 6  is a cross sectional diagram of a part of the bellows unit  28 .  FIG. 7  is an expanded diagram of the bellows unit  28 . 
     As shown in  FIG. 6  and  FIG. 7 , the bellows unit  28  includes eight plates  28   a , and a bendable connecting unit  28   b  that connects the plates  28   a  and is bendable. The plates  28   a  are formed by overlays of a flexible film member  28   c  and plate-shaped members  28   d  fixed on the film member  28   c  by an adhesive. The bendable connecting unit  28   b  is formed by the film member  28   c . The plate-shaped members  28   d  are formed by synthetic resin such as polyethylene. The plate-shaped members  28   d  do not have flexibility. A shape of the plate-shaped members  28   d  is trapezoidal. 
     It should be noted that, the plate-shaped members  28   d  (see  FIG. 6 ) forming the two plates  28   a  on the right end in  FIG. 7  and the plate-shaped members  28   d  (see  FIG. 6 ) forming the two plates  28   a  on the left end in  FIG. 7  are connected to each other via a flexible film member that is fixed to themselves by an adhesive, and which is not shown. That is, the plate-shaped members  28   d  forming the two plates  28   a  on the right end and the plate-shaped members  28   d  forming the two plates  28   a  on the left end are bendably connected to each other via this film member. As this film member, a part of the film member  28   c  (see  FIG. 6 ) may alternatively be used. 
     The case  21  and the bellows unit  28  shown in  FIG. 5  are connected to each other through a flexible film member that is fixed to themselves by an adhesive, and which is not shown. That is, the bellows unit  28  is connected bendably to the case  21  via this film member. As this film member, a part of the film member  28   c  of the bellows unit  28  (see  FIG. 6 ) may alternatively be used. 
     The pressure receiving plate  26  and the bellows unit  28  shown in  FIG. 5  are connected to each other via a flexible film member that is fixed to themselves by an adhesive, and which is not shown. That is, the bellows unit  28  is connected bendably to the pressure receiving plate  26  via this film member. As this film member, a part of the film member  28   c  of the bellows unit  28  (see  FIG. 6 ) may alternatively be used. 
     Next, a manufacturing method of the damper device  20  will be described. 
     Firstly, after the O-ring  25  is fixed to the case  21 , the rod member  27  is inserted into the hole  21   a  of the case  21 , and the spring  24  is fixed to the valve  23 . 
     Then, the cover  22  is fixed to the case  21  by an adhesive. Accordingly, the spring  24  is fixed to the cover  22  and the valve  23 . 
     Finally, the bellows unit  28  is fixed to the case  21  and the pressure receiving plate  26  by an adhesive. 
     Next, an operation of the damper device  20  will be described. 
     When the recording head  11   c  discharges the ink  10   c , an amount of the ink  10   c  in the head-side chamber  20   a  of the damper device  20  decreases. When the amount of the ink  10   c  in the head-side chamber  20   a  decreases, a volume of the head-side chamber  20   a  decreases, whereby the pressure receiving plate  26  moves in a direction shown by an arrow  20   g  accompanying contraction of the bellows unit  28 . Here, if the pressure receiving plate  26  is making contact with the rod member  27 , the valve  23  cannot move in the direction shown by the arrow  20   g  if a sum of force received from the pressure receiving plate  26  through the rod member  27  and force received by pressure of the ink  10   c  on a communicating passage  20   e  side is equal to or less than a sum of force received from the spring  24  and force received by pressure of the ink  10   c  on a tank-side chamber  20   c  side. If the valve  23  cannot move in the direction shown by the arrow  20   g , the pressure receiving plate  26  connected to the valve  23  via the rod member  27  also cannot move in the direction shown by the arrow  20   g . If the pressure receiving plate  26  cannot move in the direction shown by the arrow  20   g , since the ink  10   c  in the head-side chamber  20   a  decreases in amount while the volume of the head-side chamber  20   a  is constant, the pressure drops. 
     When the pressure of the ink  10   c  in the head-side chamber  20   a  drops, force by which the pressure receiving plate  26 , which is receiving the pressure of the ink  10   c  of the head-side chamber  20   a  and the air pressure, pushes the valve  23  via the rod member  27  is increased. 
     The valve  23  moves in the direction shown by the arrow  20   g  when the sum of the force received from the pressure receiving plate  26  through the rod member  27  and the force received by the pressure of the ink  10   c  on the communicating passage  20   e  side becomes larger than the sum of the force received from the spring  24  and the force received by the pressure of the ink  10   c  of the tank-side chamber  20   c . That is, the valve  23  opens the communicating passage  20   e . At this occasion, the pressure receiving plate  26  that is pushing the valve  23  in the direction shown by the arrow  20   g  through the rod member  27  moves in the direction shown by the arrow  20   g  accompanying the movement of the valve  23  in the direction shown by the arrow  20   g . Further, the bellows unit  28  compresses accompanying the movement of the pressure receiving plate  26  in the direction shown by the arrow  20   g.    
     Accordingly, the damper device  20  changes from a state shown in  FIG. 3  to a state shown in  FIG. 8 . 
       FIG. 8  is a front side cross sectional diagram of the damper device  20  in the situation where the valve  23  is opening the communicating passage  20   e.    
     The ink  10   c  in the tank-side chamber  20   c  is receiving high pressure by the tank  13  being at a higher position than the tank-side chamber  20   c , thus when the damper device  20  comes to be in the state shown in  FIG. 8 , it passes through the communicating passage  20   e  and is guided into the head-side chamber  20   a.    
     When the ink  10   c  is guided from the tank-side chamber  20   c  into the head-side chamber  20   a , the amount of the ink  10   c  in the head-side chamber  20   a  increases. When the amount of the ink  10   c  in the head-side chamber  20   a  is increased, the volume of the head-side chamber  20   a  is increased, whereby the pressure receiving plate  26  moves in a direction shown by an arrow  20   f  accompanying the expansion of the bellows unit  28 . 
     When the pressure receiving plate  26  moves in the direction shown by the arrow  20   f , the valve  23  that is pressed against the pressure receiving plate  26  via the rod member  27  by the biasing force of the spring  24  moves in the direction shown by the arrow  20   f  accompanying the movement of the pressure receiving plate  26  in the direction shown by the arrow  20   f . That is, the valve  23  closes the communicating passage  20   e.    
     Accordingly, the damper device  20  changes from the state shown in  FIG. 8  back to the state shown in  FIG. 3 . 
     As described above, since the damper device  20  changes the position of the pressure receiving plate  26  by the folding deformation of the bellows unit  28  instead of changing the position of the pressure receiving plate  26  by the deformation of the flexible film member itself as had conventionally been necessary, the conventional flexible film member that extends in a direction that is vertical to the direction of the arrow  20   f  or the arrow  20   g  along which the valve  23  opens or closes the communicating passage  20   e  and supports the pressure receiving plate  26  so that the position of the pressure receiving plate  26  is changeable is no longer necessary. Accordingly, the damper device  20  can make its size in the direction that is vertical to the direction shown by the arrow  20   f  or the arrow  20   g  smaller than the conventional configuration. 
     It should be noted that, since the damper device  20  does not require the conventional flexible film member that extends in the direction that is vertical to the direction shown by the arrow  20   f  or the arrow  20   g  and supports the pressure receiving plate  26  so that the position of the pressure receiving plate  26  is changeable, an area of the pressure receiving plate  26  in the direction that is vertical to the direction shown by the arrow  20   f  or the arrow  20   g  can be made larger than the conventional configuration. Accordingly, the damper device  20  can easily receive the force needed for the valve  23  to open the communicating passage  20   e  by the air pressure using the pressure receiving plate  26 . 
       FIG. 9  is a cross sectional diagram of a part of the bellows unit  28 , and is a diagram showing a different example from the example shown in  FIG. 6 . 
     The bellows unit  28  described as above has a structure shown in  FIG. 6 . However, the bellows unit  28  may have a structure shown in  FIG. 9 . In  FIG. 9 , the bellows unit  28  is formed by having the plates  28   a  and the bendable connecting unit  28   b  connecting the plates  28   a  and being bendable formed as one component made of synthetic resin such as polyethylene. In  FIG. 9 , the bendable connecting unit  28   b  is formed thinner compared to the plates  28   a  so as to be bendable. 
     If the bellows unit  28  has the structure shown in  FIG. 9 , the damper device  20  can have the plates  28   a  and the bendable connecting unit  28   b  manufactured by integral formation of synthetic resin. Accordingly, if the bellows unit  28  has the structure shown in  FIG. 9 , the damper device  20  can reduce for example manufacturing cost compared to the case where the bellows unit  28  has the structure shown in  FIG. 6 . 
       FIG. 10  is a front side cross sectional diagram of the damper device  20  in the situation where the valve  23  is closing the communicating passage  20   e , and is a diagram showing a different example from the example shown in  FIG. 3 . 
     As shown in  FIG. 10 , the damper device  20  may provide a spring  29  between the case  21  and the pressure receiving plate  26 . In case of having the structure shown in  FIG. 10 , the damper device  20  can surely maintain the pressure of the ink  10   c  of the head-side chamber  20   a  to be a negative pressure relative to the air pressure. 
       FIG. 11  is a front side cross sectional diagram of the damper device  20  in the situation where the valve  23  is closing the communicating passage  20   e , and is a diagram showing a different example from the examples shown in  FIG. 3  and  FIG. 10 . 
     The rod member  27  described as above is formed as one component made of synthetic resin such as polyethylene together with the valve  23 . However, as shown in  FIG. 11 , the rod member  27  may be formed as one component made of synthetic resin such as polyethylene together with the pressure receiving plate  26 . 
     Second Embodiment 
     Firstly, a configuration of an inkjet printer according to the present embodiment will be described. 
     It should be noted that, among the configurations in the inkjet printer according to the present embodiment, those similar to the configurations of the inkjet printer  10  according to the first embodiment (see  FIG. 1 ) will be given the same reference signs as the configuration of the inkjet printer  10 , and detailed descriptions thereof will be omitted. 
       FIG. 12  is a front side cross sectional diagram of a damper device  120  of the inkjet printer according to the present embodiment in the situation where the valve  23  closes the communicating passage  20   e .  FIG. 13  is a front side diagram of the damper device  120 .  FIG. 14  is a planar diagram of the damper device  120 . 
     A configuration of the inkjet printer according to the present embodiment is similar to a configuration in which the inkjet printer  10  (see  FIG. 1 ) includes the damper device  120  shown in  FIG. 12  to  FIG. 14  instead of the damper device  20  (see  FIG. 3 ). 
     Compared to the damper device  20 , the damper device  120  includes a case  121  in which a passage  20   b  and a passage  20   d  are formed, and a pressure receiving plate  126  as the pressure receiving unit that receives the air pressure and changes the volume of the head-side chamber  20   a  according to a change in the position of itself, instead of the case  21  (see  FIG. 3 ) and the pressure receiving plate  26  (see  FIG. 3 ). Further, the damper device  120  includes a shaft  130  that rotatably supports the pressure receiving plate  126 . 
     The head-side chamber  20   a  is formed by the case  121 , the pressure receiving plate  126  and the bellows unit  28 . 
     The case  121  is formed by synthetic resin such as polyethylene. The case  121  has the cover  22  fixed by an adhesive. 
     The pressure receiving plate  126  is formed by synthetic resin such as polyethylene. The pressure receiving plate  126  does not have flexibility. 
     The shaft  130  is supported by the case  121 . The shaft  130  extends in the direction that is vertical to the direction shown by the arrow  20   f  or the arrow  20   g.    
     Next, a manufacturing method of the damper device  120  will be described. 
     Firstly, after the o-ring  25  is fixed to the case  121 , the rod member  27  is inserted into the hole  21   a  of the case  121 , and the spring  24  is fixed to the valve  23 . 
     Then, the cover  22  is fixed to the case  121  by an adhesive. Accordingly, the spring  24  is fixed to the cover  22  and the valve  23 . 
     Then, the bellows unit  28  is fixed to the case  121  and the pressure receiving plate  126  by an adhesive. 
     Finally, the shaft  130  is fixed to the case  121  by an adhesive in a state where the shaft  130  is inserted into a hole of the case  121  and a hole of the pressure receiving plate  126 . 
     Next, an operation of the damper device  120  will be described. 
     When the recording head  11   c  discharges the ink  10   c , the amount of the ink  10   c  in the head-side chamber  20   a  of the damper device  120  decreases. When the amount of the ink  10   c  in the head-side chamber  20   a  decreases, the volume of the head-side chamber  20   a  decreases, whereby the pressure receiving plate  126  rotates in a direction shown by an arrow  120   a  with the shaft  130  as a center, accompanying contraction of the bellows unit  28 . Here, if the pressure receiving plate  126  is making contact with the rod member  27 , the valve  23  cannot move in the direction shown by the arrow  20   g  if a sum of force received from the pressure receiving plate  126  through the rod member  27  and force received by pressure of the ink  10   c  on the communicating passage  20   e  side is equal to or less than the sum of force received from the spring  24  and force received by pressure of the ink  10   c  on the tank-side chamber  20   c . If the valve  23  cannot move in the direction shown by the arrow  20   g , the pressure receiving plate  126  connected to the valve  23  through the rod member  27  also cannot rotate in the direction shown by the arrow  120   a  with the shaft  130  as the center. If the pressure receiving plate  126  cannot rotate in the direction shown by the arrow  120   a  with the shaft  130  as the center, since the ink  10   c  in the head-side chamber  20   a  decreases in amount while the volume of the head-side chamber  20   a  is constant, the pressure drops. 
     When the pressure of the ink  10   c  in the head-side chamber  20   a  drops, the force by which the pressure receiving plate  126 , which is receiving the pressure of the ink  10   c  of the head-side chamber  20   a  and the air pressure, pushes the valve  23  via the rod member  27  is increased. 
     The valve  23  moves in the direction shown by the arrow  20   g  when the sum of the force received from the pressure receiving plate  126  through the rod member  27  and the force received by the pressure of the ink  10   c  on the communicating passage  20   e  side becomes larger than the sum of the force received from the spring  24  and the force received by the pressure of the ink  10   c  of the tank-side chamber  20   c . That is, the valve  23  opens the communicating passage  20   e . At this occasion, the pressure receiving plate  126  that is pushing the valve  23  in the direction shown by the arrow  20   g  through the rod member  27  rotates in the direction shown by the arrow  120   a  with the shaft  130  as the center, accompanying the movement of the valve  23  in the direction shown by the arrow  20   g . Further, the bellows unit  28  compresses accompanying the rotation of the pressure receiving plate  126  in the direction shown by the arrow  120   a  with the shaft  130  as the center. 
     Accordingly, the damper device  120  changes from a state shown in  FIG. 12  to a state shown in  FIG. 15 . 
       FIG. 15  is a front side cross sectional diagram of the damper device  120  in the situation where the valve  23  is opening the communicating passage  20   e.    
     The ink  10   c  in the tank-side chamber  20   c  is receiving high pressure by the tank  13  being at a higher position than the tank-side chamber  20   c , thus when the damper device  120  comes to be in the state shown in  FIG. 15 , it passes through the communicating passage  20   e  and is guided into the head-side chamber  20   a.    
     When the ink  10   c  is guided from the tank-side chamber  20   c  into the head-side chamber  20   a , the amount of the ink  10   c  in the head-side chamber  20   a  increases. When the amount of the ink  10   c  in the head-side chamber  20   a  increases, the volume of the head-side chamber  20   a  increases, whereby the pressure receiving plate  126  rotates in the direction shown by an arrow  120   b  with the shaft  130  as the center, accompanying expansion of the bellows unit  28 . 
     When the pressure receiving plate  126  rotates in the direction shown by the arrow  120   b  with the shaft  130  as the center, the valve  23  that is pressed against the pressure receiving plate  126  via the rod member  27  by the biasing force of the spring  24  moves in the direction shown by the arrow  20   f  accompanying the rotation of the pressure receiving plate  126  in the direction shown by the arrow  120   b  with the shaft  130  as the center. That is, the valve  23  closes the communicating passage  20   e.    
     Accordingly, the damper device  120  changes from the state shown in  FIG. 15  back to the state shown in  FIG. 12 . 
     As described above, since the damper device  120  changes the position of the pressure receiving plate  126  by the folding deformation of the bellows unit  28  instead of changing the position of the pressure receiving plate  126  by the deformation of the flexible film member itself as had conventionally been necessary, the conventional flexible film member that extends in the direction that is vertical to the direction shown by the arrow  20   f  or the arrow  20   g  and supports the pressure receiving plate  126  so that the position of the pressure receiving plate  126  is changeable is no longer necessary. Accordingly, the damper device  120  can make its size in the direction that is vertical to the direction shown by the arrow  20   f  or the arrow  20   g  smaller than the conventional configuration. 
     It should be noted that, since the damper device  120  does not require the conventional flexible film member that extends in the direction that is vertical to the direction shown by the arrow  20   f  or the arrow  20   g  and supports the pressure receiving plate  126  so that the position of the pressure receiving plate  126  is changeable, the area of the pressure receiving plate  126  in the direction that is vertical to the direction shown by the arrow  20   f  or the arrow  20   g  can be made larger than the conventional configuration. Accordingly, the damper device  120  can easily receive the force needed for the valve  23  to open the communicating passage  20   e  by the air pressure using the pressure receiving plate  126 . 
     Since the damper device  120  has the pressure receiving plate  126  rotatably supported, in the situation where the valve  23  is to transmit force to the pressure receiving plate  126  through the rod member  27  at a distant position from the shaft  130  being the rotation center of the pressure receiving plate  126  as shown in  FIG. 12 , a moving amount of the valve  23  relative to a decreased amount of the ink  10   c  in the head-side chamber  20   a  can be increased, compared to the configuration in which the entirety of the pressure receiving plate  126  moves in the direction shown by the arrow  20   f  or the arrow  20   g  as in the damper device  20  according to the first embodiment. Accordingly, the damper device  120  can reduce the pressure fluctuation of the ink  10   c  in the head-side chamber  20   a , as a result of which discharging accuracy of the ink  10   c  by the recording head  11   c  can be stabilized. 
       FIG. 16  is a front side cross sectional diagram of the damper device  120  of the inkjet printer according to the present embodiment in the situation where the valve  23  is closing the communicating passage  20   e , and is a diagram showing a different example from the example shown in  FIG. 12 . 
     Since the damper device  120  shown in  FIG. 16  has the rod member  27  making contact with the pressure receiving plate  126  in the vicinity of the shaft  130 , the force by which the pressure receiving plate  126  pushes the rod member  27  becomes large even if the force that the pressure receiving plate  126  receives from the air pressure is small, due to a principle of leverage. That is, since the damper device  120  has the pressure receiving plate  126  rotatably supported, when the valve  23  is to transmit force to the pressure receiving plate  126  through the rod member  27  in the vicinity of the shaft  130  being the rotation center of the pressure receiving plate  126  as shown in  FIG. 16 , the pressure receiving plate  126  can obtain the force needed for the valve  23  to open the communicating passage  20   e  from the air pressure even if the size of the pressure receiving plate  126  in the direction that is vertical to the direction shown by the arrow  20   f  or the arrow  20   g  is made compact, as compared to the configuration in which the entirety of the pressure receiving plate  126  moves in the direction shown by the arrow  20   f  or the arrow  20   g.    
       FIG. 17  is a front side cross sectional diagram of the damper device  120  of the inkjet printer according to the present embodiment in the situation where the valve  23  is closing the communicating passage  20   e , and is a diagram showing a different example from the examples shown in  FIG. 12  and  FIG. 16 . 
     In the damper device  120  shown in  FIG. 17 , the pressure receiving plate  126  and the case  121  being a supporting unit that rotatably supports the pressure receiving plate  126  are formed as one component formed of synthetic resin such as polyethylene. A portion  131  that enables the pressure receiving plate  126  to be rotatable relative to the case  121  in  FIG. 17  is formed thin compared to the case  121  and the pressure receiving plate  126 . 
     If the damper device  120  has the structure shown in  FIG. 17 , the case  121  and the pressure receiving plate  126  can be manufactured by integral formation of synthetic resin. Accordingly, if the damper device  120  has the structure shown in  FIG. 17 , for example the manufacturing cost can be reduced compared to the case of the structure shown in  FIG. 12 . 
       FIG. 18  is a front side cross sectional diagram of the damper device  120  of the inkjet printer according to the present embodiment in the situation where the valve  23  is closing the communicating passage  20   e , and is a diagram showing a different example from the examples shown in  FIG. 12 ,  FIG. 16 , and  FIG. 17 . 
     In the damper device  120  shown in  FIG. 18 , the case  121  and the pressure receiving plate  126  are connected to each other via a flexible film member  132  that is fixed to themselves by an adhesive. That is, the pressure receiving plate  126  is supported rotatably by the case  121  via the film member  132 .