JP2012171343A - Pressure buffer, liquid injection head, and liquid injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a pressure over a wide dynamic range by improving linearity of displacement with respect to pressure variation of a liquid packed inside.SOLUTION: A pressure buffer 1 includes: a base body 2 having a recess 4 open upward and a communication hole 5 in the inner surface of the recess 4 to communicate with an external region; a buffer member 3 that joins the upper end surface of the recess 4 to close the opening of the recess 4 and buffers pressure variation of a liquid filled inside; and a detecting section 10 that detects relative displacement between the buffer member 3 and the base body 2. The buffer member 3 includes a plate body 3a having a flat center part and an elastic body 3b having a ring peripheral part. The elastic body 3b is made to be bent into a U-shape in a radial direction.

Description

  The present invention relates to a pressure buffer that relaxes fluid pressure fluctuations, and more particularly to a pressure buffer having a function of converting fluid pressure fluctuations into an electrical signal, a liquid ejecting head using the same, and a liquid ejecting apparatus.

  In recent years, ink jet type liquid ejecting heads have been used in which ink droplets are ejected onto recording paper or the like to draw characters and figures, or liquid material is ejected onto the surface of an element substrate to form a functional thin film. In this method, ink or liquid material is supplied from a liquid tank to a liquid ejecting head via a supply pipe, and ink or liquid material filled in the channel is discharged from a nozzle communicating with the channel. When ink is ejected, a liquid ejecting head or a recording medium for recording the ejected liquid is moved to record characters and figures, or a functional thin film having a predetermined shape is formed. In this type of apparatus, it is necessary to control the ink pressure of the nozzle discharge section with high accuracy in order to control the discharge amount and discharge speed when discharging droplets from the nozzle.

  Patent Document 1 describes an ink jet recording apparatus that includes a mechanism for adjusting the pressure of a liquid discharged from a print head. This ink jet recording apparatus includes a base tank that stores ink, a sub tank that receives ink supplied from the base tank and supplies ink to the ink jet head, a pump that adjusts the internal pressure in the sub tank, and a pressure that is installed for supplying ink. Has a meter. In this ink jet recording apparatus, the ink internal pressure is controlled by adjusting the internal pressure in the sub tank according to the use state. For example, when discharging high-viscosity ink or performing bubble discharge operation by preliminary discharge, the negative pressure acting on the ink is controlled to be smaller than that during printing.

  Patent Document 2 describes a damper structure for absorbing pressure fluctuations in the ink discharge section. As shown in FIG. 11 (FIG. 1 of Patent Document 2), the recess 101b formed in the base 101 communicates with the supply groove 101a for supplying ink via the communication groove 101c. Upper portions of the recess 101b, the communication groove 101c, and the supply groove 101a are closed by a diaphragm 102. At the center of the diaphragm 102, a corrugated portion 102a composed of concentric annular concavo-convex portions is formed. Since the diaphragm 102 itself has elasticity, a spring member is not required, the number of parts and the number of assembly steps can be reduced, and the cost can be reduced. Patent Document 3 describes a pressure buffer used for an inkjet head. This pressure shock absorber has a structure in which a chamber formed of a recess is formed on the surface of a main body, and a flexible film is attached to the opening of the recess. Since the flexible membrane itself has elasticity, it is possible to absorb pressure fluctuations of the liquid.

JP 2005-231351 A JP-A-7-164638 JP 2008-110599 A

  However, in the ink jet recording apparatus described in Patent Document 1, a pressure gauge is connected to a pipe branched from a part of the liquid supply path. Therefore, the liquid flowing through the liquid supply path may enter the pressure gauge side. The liquid ejecting head reciprocates at high speed. In particular, when the moving direction of the liquid ejecting head is reversed or accelerated rapidly, the internal pressure fluctuates due to the inertia of the liquid in the pipe. Due to this pressure fluctuation, the liquid entered the inside of the pressure gauge, and the ink or liquid that entered further thickened or solidified to reduce the detection accuracy of the pressure gauge. As a result, there have been problems such as insufficient pressure control of ink and liquid material, resulting in a decrease in recording quality.

  In recent years, this type of apparatus has been increased in size and recording speed. Along with the increase in size of the apparatus, the piping distance between a liquid tank of fixed ink or the like and the moving liquid jet head has become longer. Normally, in this type of apparatus, the internal pressure of the liquid in the discharge region is controlled in order to make the liquid meniscus at the nozzle of the liquid jet head and the discharge speed of the liquid droplets discharged from the nozzle constant. However, as the piping distance increases, the flow resistance of the liquid flowing inside increases, and the pressure loss due to the flow path increases. Further, as the moving distance and moving speed of the liquid ejecting head increase, the internal pressure fluctuation due to the inertia of the liquid also increases. For this reason, it is necessary to control the internal pressure of the liquid in the discharge region with higher accuracy, and it is necessary to further strengthen the buffer function for reducing fluctuations in the internal pressure of the liquid.

  Therefore, it is conceivable to install a pressure gauge in a pressure buffer attached in the immediate vicinity of the liquid jet head. For example, there can be considered a method in which a position detection unit is provided in the movable part of the damper structure described in Patent Document 2, that is, the corrugated part 102a of the diaphragm 102, and the pressure of the liquid filled therein is detected by detecting the position of the diaphragm. Alternatively, a method is conceivable in which a position detection unit is provided in the flexible film of the pressure buffer described in Patent Document 3, and the pressure of the liquid filled therein is detected by detecting the position of the flexible film.

  However, since the diaphragm of Patent Document 2 uses a polysulfone resin, it has high hardness and a small stroke with respect to pressure fluctuation of the internal liquid. Therefore, the pressure fluctuation detection range is narrow. Further, the central portion of the corrugated portion 102a is displaced in multiple directions with respect to the pressure fluctuation of the internal liquid. Therefore, even if the displacement in the perpendicular direction at the center is measured, the pressure change inside the liquid is not measured with high accuracy.

  Further, a method for detecting the pressure fluctuation of the liquid filled inside by installing a position detector on the flexible film described in Patent Document 3 is conceivable. However, like the above-mentioned Patent Document 2, the position detection unit installed on the flexible membrane is displaced in multiple directions with respect to the pressure fluctuation of the internal liquid, and the pressure change inside the liquid cannot be measured with high accuracy. Further, in order to utilize the stretchability of the flexible membrane, the position displacement stroke with respect to pressure fluctuation is small, and the dynamic range of pressure detection is narrow. Moreover, although a flexible film | membrane is affixed on the upper surface of a recessed part by heat welding, it is difficult to affix the tension | tensile_strength of a film | membrane uniformly. For this reason, variations in tension, wrinkles and local slack are likely to occur after application. When wrinkles or slack occur, the shape or location of wrinkles or slack changes according to pressure changes. As a result, the linearity of the position displacement with respect to the pressure fluctuation is reduced, and the hysteresis characteristic and the discontinuous characteristic appear and the accuracy is lowered.

  This invention is made | formed in view of such a subject, and provides the pressure buffer which can detect the pressure fluctuation of a liquid with high precision.

  The pressure shock absorber according to the present invention has a concave portion whose upper end is open, a main body portion having a communication hole communicating with an external region on the inner surface of the concave portion, and is bonded to the upper end surface of the concave portion to close the opening of the concave portion, A buffer member that relieves pressure fluctuation of the liquid filled therein, and a detection unit that detects a relative position change between the buffer member and the main body, and the buffer member has a plate at the center. The elastic body is made of an elastic body, and the elastic body has a bending section in the radial direction.

  Further, the elastic body has a ring shape surrounding the periphery of the plate-like body.

  In addition, the deflection is U-shaped.

  The bend is convex on the concave side.

  Further, the bending is convex on the opposite side to the concave portion.

  Moreover, the said bending bent the convex to the side of the said recessed part, and the convex to the opposite side to the said recessed part.

  The plate-like body and the elastic body are made of the same material, and the plate-like body is thicker than the elastic body.

  The plate-like body is made of a conductive material or a magnetic material.

  Further, a spring member that engages one end with the plate-like body and the other end with the main body is provided.

  Further, the detection unit detects the relative position change by detecting an electromotive force based on electromagnetic induction.

  In addition, the detection unit includes a transmission coil that generates lines of magnetic force and a reception coil that induces the electromotive force.

  According to another aspect of the invention, there is provided a liquid jet head including the pressure buffer according to any one of the above, a pipe communicating with the communication hole of the pressure buffer, and an actuator that discharges the liquid flowing in from the pipe.

  The liquid ejecting apparatus according to the aspect of the invention includes the liquid ejecting head, a tank that stores the liquid and supplies the liquid to the pipe, and the pressure of the liquid based on the relative position change detected by the pressure buffer. And a pump to be controlled.

  The pressure shock absorber according to the present invention has a concave portion whose upper end is open, a main body portion having a communication hole communicating with an external region on the inner surface of the concave portion, and the upper end surface of the concave portion which is closed to close the opening and is filled inside. A buffer member that alleviates the pressure fluctuation of the liquid, and a detection unit that detects a relative position change between the buffer member and the main body. Furthermore, the buffer member is made of a plate-like body having a flat central portion, and its peripheral portion is made of an elastic body, and the elastic body has a cross section that is bent in the radial direction. Thereby, the linearity of the detection position with respect to pressure fluctuation can be improved, and the detectable dynamic range and detection sensitivity can be improved.

It is explanatory drawing of the pressure buffer which concerns on 1st embodiment of this invention. It is a graph for demonstrating the characteristic of the pressure buffer of this invention. It is explanatory drawing of the main body detection part of the pressure buffer which concerns on 1st embodiment of this invention. It is a circuit block diagram of the main-body detection part of the pressure buffer which concerns on 1st embodiment of this invention. It is a typical longitudinal section of a pressure buffer concerning a second embodiment of the present invention. It is a typical longitudinal section of a pressure buffer concerning a third embodiment of the present invention. It is a typical longitudinal section of a pressure buffer concerning a 4th embodiment of the present invention. FIG. 10 is a perspective view of a liquid jet head according to a fifth embodiment of the invention. FIG. 10 is an exploded perspective view of a pressure buffer of a liquid jet head according to a fifth embodiment of the present invention. FIG. 10 is a schematic perspective view of a liquid ejecting apparatus according to a sixth embodiment of the present invention. It is a schematic diagram of a conventionally well-known damper structure.

(First embodiment)
FIG. 1 is an explanatory view of a pressure shock absorber according to a first embodiment of the present invention, FIG. 1 (a) is a schematic longitudinal sectional view of the pressure shock absorber 1, and FIG. 1 (b) is a shock absorber 3. It is a typical perspective view. As shown in FIG. 1, the pressure shock absorber 1 includes a main body 2 having a recess 4 with an upper end opened, a buffer member 3 that is bonded to the upper end surface of the recess 4 and closes the opening, and a buffer member 3. The detection part 10 which detects the relative position change between main body parts is provided. The main body 2 includes communication holes 5 a and 5 b that communicate with an external region on the inner surface of the recess 4. A cover 17 is fixed to the upper surface of the recess 4 so as to cover the buffer member 3 at the top of the buffer member 3. The buffer member 3 includes a plate-shaped body 3a at the center and an elastic body 3b having a ring-shaped periphery. The plate-like body 3a has a flat surface. The elastic body 3b has a U-shaped cross section in the radial direction. (The U-shaped deflection means a shape in which the cross section in the radial direction of the elastic body 3b is substantially semicircular and protrudes in the direction of the interior 6 or the direction of the cover 17. The same applies hereinafter.) Is directed downward on the liquid side of the recess 4. The detection unit 10 includes a main body detection unit 10a and a detected portion 10b. The main body detection portion 10a is installed on the inner surface of the cover 17 on the buffer member 3 side, and the detected portion 10b is installed on the surface of the plate-like body 3a on the cover 17 side. ing.

  The recess 4 includes a communication hole 5a through which a liquid such as ink flows, and a communication hole 5b through which the liquid with reduced pressure fluctuations flows out. The room 6 surrounded by the recess 4 and the detection unit 10 is filled with liquid. In this state, when pressure fluctuation is transmitted through the communication hole 5a, the elastic body 3b of the buffer member 3 is deformed, and the plate-like body 3a is displaced up and down. Due to the displacement of the plate-like body 3a, the pressure fluctuation of the liquid in the chamber 6 is alleviated, and the pressure fluctuation is not transmitted to the liquid flowing out from the communication hole 5b. The detection unit 10 detects a distance from the detected unit 10b that is displaced along with the displacement of the plate-like body 3a. The detection unit 10 detects a pressure change of the liquid from the detected displacement of the distance.

  That is, the plate-like body 3a is displaced in the vertical direction indicated by the arrow without being inclined or displaced in the lateral direction with respect to the pressure fluctuation of the liquid. Furthermore, since the elastic body 3b is previously formed into a U shape, wrinkles and slack are less likely to occur when, for example, heat welding is performed on the upper surface of the recess 4. Therefore, the linearity of the position change with respect to the pressure change is improved, and the hysteresis is also reduced. Further, since the elastic body 3b does not use the elasticity accompanying the expansion and contraction of the film but uses the bending elasticity of the film, the amount of displacement of the detected portion 10b increases, and the dynamic range of the detected pressure can be increased. Further, the elastic body 3b can be formed thicker than the conventional flexible film. Therefore, it is possible to suppress the membrane permeability of a substance such as oxygen, to prevent deterioration of the internal liquid, and to improve the reliability.

  A polymer material can be used as the main body 2 and the buffer member 3. For example, a polyethylene material can be used. In this case, a high density polyethylene material (hereinafter referred to as HDPE) is used as the main body 2 or the plate-like body 3a, and a low density polyethylene material (hereinafter referred to as LDPE) is used as the elastic body 3b. it can. Since it is the same polyethylene material, if the buffer member 3 is heat-welded to the upper end surface of the recessed part 4, high airtightness can be maintained. The plate-like body 3a may be joined to the ring-shaped elastic body 3b by heat welding using HDPE, or the same LDPE as the plate-like body 3a is used, and the thickness thereof is thicker than the surrounding elastic body 3b. It may be difficult to form and deform. As the elastic body 3b, LDPE having a thickness of 100 μm to 150 μm can be used.

  The features of the pressure buffer according to the present invention will be described with reference to FIG. In FIG. 2, the horizontal axis represents the pressure (p) of the liquid filled in the chamber 6, and the vertical axis represents the displacement amount (D) of the detected part 10b with respect to the main body detecting part 10a. As for the amount of displacement, + D is the room 6 side, and -D is the main body detection unit 10a side. A solid line graph G1 is a characteristic of the pressure buffer of the present invention, and a broken line graph G2 is a characteristic of a conventional pressure buffer using a stretchable flexible film as the buffer member 3. The pressure buffer according to the present invention has (1) a wide movable range of the diaphragm (the plate-like body 3a in FIG. 1) and (2) good linearity with respect to the pressure change of the liquid as compared with the conventional pressure buffer. (3) It has a feature of low hysteresis. In addition, the arrow in a graph represents the transition direction of a pressure and a displacement amount.

(1) The pressure buffer of the present invention has a wide movable range of the diaphragm. That is, in the prior art, the movable range is ensured by the stretchability of the material constituting the flexible film. However, the amount of expansion / contraction has to be within a limited range that does not cause plastic deformation in the film. For this reason, the movable range of the usable film surface has been limited to a very limited range. On the other hand, in the pressure buffer of the present invention, it is possible to give a larger free movable range by utilizing the elastic deformation of the elastic body formed in a U shape in advance.
(2) The pressure buffer of the present invention has good linearity. That is, in the prior art, as the pressure increases, the flexible membrane becomes tense and the amount of change in the membrane decreases. For this reason, the displacement amount with respect to the pressure change does not move linearly proportionally, but has a characteristic of drawing a curve including a saturation region of displacement at both positive and negative pressure ends. On the other hand, in the pressure buffer of the present invention, the pressure range in which the diaphragm is linearly displaced can be broadened by utilizing the elastic deformation of the U-shaped portion of the elastic body, that is, the bending elasticity of the thin plate material constituting the elastic body. It can be secured. For example, if the target pressure detection range is set to +5 kPa to -5 kPa, it is easy to cover the range with linear displacement characteristics.
(3) The pressure buffer of the present invention has little hysteresis. That is, in the prior art, there is a region where the locus of displacement does not match between when the pressure transitions in the pressurizing direction and when the pressure transitions in the depressurizing direction due to the looseness of the film that occurs when the flexible film is welded to the main body. . In addition, the flexible film made of a polymer material has a slow temporal response when stretched and restored, and the displacement of the film surface is delayed with respect to pressure fluctuation. For this reason, a large hysteresis occurs in the displacement amount. In contrast, the pressure shock absorber of the present invention supports the plate-like body in advance at a predetermined reference position by a molded elastic body, and smoothly smoothes the plate-like body in the vertical direction while keeping the plate-like body horizontal by elastic deformation of the U-shaped portion. It is displaced to. Therefore, there is no discontinuous displacement characteristic during pressure transition due to membrane loosening as in the prior art. In addition, since the slow response film stretching / restoration is not used, good displacement responsiveness can be obtained.

  In addition, although the case where one convex downward bending was formed in the radial direction as the elastic body 3b was demonstrated, even if it forms a plurality of downward convex bending, the effect of this invention can be show | played. Further, as shown in FIG. 1A, it is preferable that a gap is formed between the convex side surface of the convex portion and the side surface of the concave portion 4 on the lower side of the elastic body 3b so that bubbles are not taken in. This is because the air bubbles taken into the gap later enter the discharge part and cause a discharge failure. In addition to the polymer material, a metal material can be used as the buffer member 3.

  FIG. 3 is an explanatory diagram illustrating the main body detection unit 10a. FIG. 3A is a schematic longitudinal sectional view of the main body detection unit 10a, and FIG. 3B is a schematic exploded perspective view of the main body detection unit 10a. As shown in FIG. 3, the main body detection unit 10 a includes a transmission coil 11 that generates magnetic field lines, a reception coil 12 that induces electromotive force, and a case 16 that houses them. More specifically, the insulating substrate 18c includes the circuit element 27 on the back surface side, and the electrode (or wiring pattern) 41b, the insulating substrate (or insulating layer) 18b, and the spiral planar transmission coil 11 on the upper surface side. , An insulating film 29b, an electrode (or wiring pattern) 41a, an insulating substrate (or insulating layer) 18a, a spiral planar receiving coil 12, and an insulating film 29a. A lead 28 that penetrates the case 16 is installed and connected to the external control unit. By adopting such a laminated structure, the main body detection unit 10a can be formed thin.

  In addition, as a modification example, the main body detection unit 10a stores the insulating substrate 18a on which the receiving coil 12 is mounted, the insulating substrate 18b on which the transmitting coil 11 is mounted, the insulating substrate 18c on which the circuit element 27 is mounted, and these. The case 16 can be provided. A spiral planar receiving coil 12 is formed on the upper surface of the insulating substrate 18a, a protective insulating film 29a is laminated on the upper surface, and a wiring that penetrates the insulating substrate 18a on the back surface of the insulating substrate 18a and connects to the receiving coil 12 The electrode 41a is formed. Similarly, a spiral planar transmission coil 11 is formed on the upper surface of the insulating substrate 18b, a protective insulating film 29b is laminated on the upper surface, and the insulating substrate 18b penetrates the back surface of the insulating substrate 18b to form the transmission coil 11. A wiring electrode 41b to be connected is formed. A circuit element 27 constituting a transmission circuit and a reception circuit is installed on the back surface of the insulating substrate 18c, and is electrically connected to the transmission coil 11 and the reception coil 12 through a wiring penetrating the insulating substrate 18c. Thereby, a laminated structure can be comprised simply.

  As described above, the receiving coil 12 and the transmitting coil 11 are stacked and arranged so that the centers coincide with each other in plan view, so that the outer shape of the main body detection unit 10a can be reduced in size. Moreover, since the receiving coil 12 and the transmitting coil 11 are flat-plate coils, the thickness of the main body detection unit 10a can be reduced. Further, a magnetic material having a high magnetic permeability can be used as the case 16. If a magnetic material with high permeability is used, the lines of magnetic force do not leak to the outside, so that it is possible to prevent the detection sensitivity from being lowered when a conductive material such as metal is used as the cover 17.

  FIG. 4 is a block diagram of the detection circuit 30 built in the main body detection unit 10a. The detection circuit 30 includes a transmission circuit 31 and a reception circuit 32. The transmitter circuit 31 includes a transmitter 33 and a transmitter coil 11 that generates a magnetic field by an alternating current input from the transmitter 33. The reception circuit 32 includes a reception coil 12 that induces an induced electromotive force by a magnetic field, a detection circuit 34 that detects the induced electromotive force, an offset circuit 35 that sets an offset of the detected reception signal, and an amplification that amplifies the reception signal. A circuit 36; a filter circuit 37 that removes a noise component from the amplified received signal; an adjustment circuit 38 that adjusts the offset value and the amplification factor; and a storage unit that stores setting values for setting the offset value and the amplification factor. 39 is provided.

  The transmission circuit 31 generates a magnetic field having a predetermined strength. The receiving circuit 32 generates an induced electromotive force from the magnetic field generated by the transmission coil 11, and detects a change in the position of the detected portion 10b based on the change in the induced electromotive force. That is, if the detected portion 10b is a conductive material, eddy currents are generated and lost due to magnetic lines that cross the detected portion 10b. If the detected portion 10b is a magnetic material, the path of the magnetic lines that cross the detected portion 10b. Is changed. Since the loss of magnetic field lines and the path change depend on the distance between the coil and the detected portion 10b, the relationship between the induced electromotive force and the distance is obtained in advance, so that the detected portion 10b is determined from the magnitude of the induced electromotive force. Can be detected. Similarly, the liquid pressure can be detected from the magnitude of the induced electromotive force by obtaining the relationship between the position of the detected portion 10b and the internal pressure of the liquid in the chamber 6 in advance. The detection circuit 30 outputs the detection result of the position displacement of the detected portion 10b from the filter circuit 37 as a detection signal.

  Here, the adjustment circuit 38 can set the offset value of the offset circuit 35 and the amplification factor of the amplification circuit 36 based on the setting data input from the external control unit. That is, when setting data is input from the outside, the adjustment circuit 38 reads a setting value corresponding to the setting data from the storage unit 39, and sets the offset value and the amplification factor of the offset circuit 35 and the amplification circuit 36. Thereby, a detection characteristic can be set freely. Further, even when there are variations in the shapes and materials of the parts constituting the pressure buffer 1, the variation in detection characteristics can be kept within a predetermined range by adjusting each individual.

  Instead of installing the detected portion 10b on the plate-like body 3a, the detected portion 10b may also be used by using a magnetic material or a conductor material as the plate-like body 3a. Further, instead of detecting a change in electromotive force based on electromagnetic induction and detecting a change in position between the main body 2 and the buffer member 3, the detection unit 10 detects a change in impedance based on the electromagnetic induction. Thus, a change in position between the main body 2 and the buffer member 3 can be detected. Further, as the detection unit 10, instead of detecting the distance based on electromagnetic induction, the distance may be measured optically or based on a change in capacitance. Moreover, in the said embodiment, although the to-be-detected part 10b was installed in the cover 17 side of the plate-shaped body 3a, you may install this in the recessed part 4 side. Moreover, in the said embodiment, although the main body detection part 10a was installed in the buffer member 3 side of the cover 17, this invention is not limited to this, You may install the main body detection part 10a in the bottom face or side surface of the recessed part 4. FIG. In short, the detected portion 10b is directly or indirectly engaged with the plate-like body 3a and displaced together with the plate-like body 3a, and the main body detecting portion 10a is directly or indirectly engaged with the main body portion 2. What is necessary is just to be fixed with respect to the plate-shaped body 3a.

(Second embodiment)
FIG. 5 is a schematic longitudinal sectional view of the pressure shock absorber 1 according to the second embodiment of the present invention. The difference from the first embodiment is that the elastic body 3b constituting the buffer member 3 has a convex U-shaped deflection on the upper side opposite to the concave portion 4. The cover 17 has a vertical side surface in the vicinity of the upper surface of the recess 4 so as not to contact the elastic body 3b. Since other configurations are the same as those of the first embodiment, description thereof is omitted. The same portions or portions having the same function are denoted by the same reference numerals.

  In the present embodiment, since the liquid is filled in the bent portion of the elastic body 3b, the depth of the recess 4 can be formed shallower than in the case of the first embodiment. Further, a narrow gap is not formed between the side surface of the convex portion of the elastic body 3 b and the side surface of the concave portion 4. Therefore, the problem of ejection failure due to the retention of bubbles does not occur. In the above-described embodiment, a case has been described in which a single upwardly projecting flexure is formed as the elastic body 3b. However, the effect of the present invention can be achieved even if a plurality of upwardly projecting flexures are provided. Can do. Similarly, the elastic body 3b may have a downward convex deflection in addition to the upward convex deflection.

(Third embodiment)
FIG. 6 is a schematic longitudinal sectional view of the pressure shock absorber 1 according to the third embodiment of the present invention. The difference from the first or second embodiment is that the elastic body 3b constituting the buffer member 3 has a downwardly convex and upwardly convex U-shaped flexure in the radial direction, and the other points are the first And it is the same as that of 2nd embodiment. The same portions or portions having the same function are denoted by the same reference numerals.

  As shown in FIG. 6, the radial cross section of the elastic body 3b has a structure in which U-shaped bending continues, and the bending stress for displacing the plate-like body 3a in the vertical direction is reduced. As a result, the vertical stroke of the plate-like body 3a increases, and the dynamic range of the detected pressure increases. In addition, the elastic body 3b can be formed thicker than in the first or second embodiment. For this reason, wrinkles and slack are less likely to occur when welding to the upper surface of the recess 4, the linearity of the position variation with respect to the pressure variation is improved, and the hysteresis characteristic can be reduced.

(Fourth embodiment)
FIG. 7 is a schematic longitudinal sectional view of the pressure shock absorber 1 according to the fourth embodiment of the present invention. The difference from the first embodiment is that a spring member 7 is installed between the buffer member 3 and the main body 2, and other configurations are the same as those of the first embodiment. The same portions or portions having the same function are denoted by the same reference numerals.

  As shown in FIG. 7, a spring member 7 made of a coil spring was installed between the plate-like body 3 a of the buffer member 3 and the bottom surface of the recess 4 of the main body 2. When a soft material or a structure with small stress for moving the plate-like body 3a up and down is employed as the elastic body 3b, the initial position of the detected part 10b may not be determined. If the spring member 7 is installed in such a case, the initial distance between the detected portion 10b and the main body portion 2 can be fixed and the initial adjustment performed individually can be simplified. The spring member 7 can be a plate spring or the like in addition to the coil spring.

In addition, by configuring the leaf spring with a conductive material or a magnetic material, the above-described detected portion 10b can be omitted. That is, a leaf spring can be used as the detected portion 10b.
Specifically, the leaf spring in the present embodiment is not completely fixed to the plate-like body 3 a, but is contracted by a predetermined amount in the expansion / contraction direction and enclosed in the main body 2. Therefore, the buffer member 3 is always in contact with the plate-like body 3a regardless of whether the buffer member 3 is displaced to the main body 2 side or the cover 17 side.
Accordingly, the leaf spring exhibits the same behavior as the plate-like body 3a in accordance with the displacement of the buffer member 3, so that the main body detection unit 10a detects the behavior of the plate spring as the behavior of the plate-like body 3a, and detects pressure fluctuation. Can do.
Although the form of the leaf spring is not shown, it is formed by an elastic portion and a plate portion, one end of the elastic portion is engaged with the main body portion 2, the other end of the elastic portion is engaged with the plate portion, and the plate portion is a plate. It is configured to face the surface on the concave portion 4 side of the body 3a.

(Fifth embodiment)
8 and 9 are diagrams for explaining the liquid jet head 20 according to the fifth embodiment of the present invention. FIG. 8 is a perspective view of the liquid jet head 20, and FIG. 9 is used for the liquid jet head 20. It is a disassembled perspective view of the pressure buffer 1 which does. The same portions or portions having the same function are denoted by the same reference numerals.

  As shown in FIG. 8, the liquid ejecting head 20 includes a base 24, an ejecting unit 22 that ejects droplets to a recording medium (not shown), a pressure buffer 1 that supplies liquid to the ejecting unit 22, and an ejecting unit 22. And a control circuit board 25 on which a control circuit for processing a detection signal received from the pressure buffer 1 is mounted. The ejection unit 22 is an unillustrated flexible actuator that electrically connects the actuator 26 and the control circuit board 25 with an actuator 26 that ejects droplets in response to a drive signal, a flow path member 23 that supplies liquid to the actuator 26, and the actuator 26. A circuit board is provided. The base 24 has a partition shape, an actuator 26 is mounted on the bottom, and the control circuit board 25 and the pressure buffer 1 are fixed to the side surfaces. The pressure shock absorber 1 is fixed to the base 24 with the cover 17 facing outward and the main body 2 facing the base 24 side.

  The liquid flows from the supply pipe 40 into the main body portion 2 through the connection portion 21a, flows into the flow path member 23 through the connection portion 21b, and further flows into the actuator 26. The actuator 26 discharges droplets onto a recording medium (not shown) in the lower part in response to a drive signal from the control circuit. Here, as the pressure buffer 1, the pressure buffer 1 of the first to fourth embodiments can be used.

  The pressure buffer 1 reduces the pressure fluctuation of the liquid that has flowed in, detects the pressure, and transmits it to the control circuit. Further, since the pressure buffer 1 is installed in the vicinity of the actuator 26 of the liquid ejecting head 20, it is possible to supply the liquid with the reduced pressure fluctuation to the actuator 26 and to detect the actual pressure fluctuation in the vicinity of the nozzle. As a result, the liquid pressure when ejecting the droplets can be controlled with high accuracy.

  As shown in FIG. 9, the pressure buffer 1 is installed on the upper surface of the recess 4, the main body 2 having the recess 4, the connection portion 21 a for liquid inflow and the connection portion 21 b for liquid outflow, and the upper end of the recess 4. And a cover 17 having a main body detection unit 10a installed on the inner surface thereof. The buffer member 3 is composed of a flat plate-like body 3a at the center and a ring-shaped elastic body 3b at the periphery. The detected part 10b was installed on the surface of the plate-like body 3a on the cover 17 side. The buffer member 3 can exhibit a pressure relaxation function against a sudden change in liquid pressure because the plate-like body 3a is displaced as a substantially free end in the vertical direction. The main body detection unit 10a detects a change in the pressure of the liquid by detecting a relative position change with the detected unit 10b installed on the plate-like body 3a.

(Sixth embodiment)
FIG. 10 is a schematic perspective view of a liquid ejecting apparatus 50 according to the sixth embodiment of the present invention. The liquid ejecting apparatus 50 uses the liquid ejecting head 20 described in the fifth embodiment. The liquid ejecting apparatus 50 includes a moving mechanism 63 that reciprocates the liquid ejecting heads 20 and 20 ′, liquid supply pipes 53 and 53 ′ that supply liquid to the liquid ejecting heads 20 and 20 ′, and liquid supply pipes 53 and 53 ′. Liquid tanks 51 and 51 'for supplying the liquid to the tank. Each of the liquid jet heads 20 and 20 ′ includes an actuator 26 that discharges the liquid, a flow path member 23 that supplies the liquid to the actuator 26, and a pressure buffer 1 that supplies the liquid to the flow path member 23.

  Here, the pressure buffer 1 suppresses fluctuations in the pressure of the liquid supplied to the flow path member 23 and the actuator 26 ahead, and detects a fluctuation in the pressure of the liquid to generate a detection signal. It transmits to the control part which is not illustrated. The control unit adjusts the pressure of the liquid supplied to the actuator 26 based on this detection signal.

  This will be specifically described. The liquid ejecting apparatus 50 includes a pair of conveying units 61 and 62 that convey a recording medium 54 such as paper in the main scanning direction, liquid ejecting heads 20 and 20 ′ that eject liquid to the recording medium 54, and a liquid tank 51. , 51 ′ presses and supplies liquid stored in the liquid supply pipes 53, 53 ′ to the liquid supply pipes 53, 53 ′, and a moving mechanism that scans the liquid jet heads 20, 20 ′ in the sub-scanning direction orthogonal to the main scanning direction. 63 etc.

  The pair of conveying means 61 and 62 includes a grid roller and a pinch roller that extend in the sub-scanning direction and rotate while contacting the roller surface. A grid roller and a pinch roller are moved around an axis by a motor (not shown), and the recording medium 54 sandwiched between the rollers is conveyed in the main scanning direction. The moving mechanism 63 connects a pair of guide rails 56, 57 extending in the sub-scanning direction, a carriage unit 58 that can slide along the pair of guide rails 56, 57, and the carriage unit 58 to move in the sub-scanning direction. An endless belt 59 is provided, and a motor 60 that rotates the endless belt 59 via a pulley (not shown) is provided.

  The carriage unit 58 mounts a plurality of liquid jet heads 20 and 20 ′, and discharges four types of liquid droplets, for example, yellow, magenta, cyan, and black. The liquid tanks 51 and 51 'store liquids of corresponding colors and supply them to the liquid jet heads 20 and 20' via the pumps 52 and 52 'and the liquid supply pipes 53 and 53'.

  The control unit of the liquid ejecting apparatus 50 gives drive signals to the liquid ejecting heads 20 and 20 ′ to eject liquid droplets of the respective colors. The control unit controls the timing at which liquid is ejected from the liquid ejecting heads 20 and 20 ′, the rotation of the motor 60 that drives the carriage unit 58, and the conveyance speed of the recording medium 54, so that an arbitrary pattern is formed on the recording medium 54. Record. Further, the control unit controls the pumps 52 and 52 ′ based on the detection signal of the pressure buffer 1 to adjust the pressure of the liquid supplied to the actuator 26. For example, when the control unit determines from the detection signal of the pressure buffer 1 that the liquid pressure is larger than the reference value, the control unit controls the pumps 52 and 52 ′ to reduce the liquid supply pressure. Further, when the control unit determines from the detection signal of the pressure buffer 1 that the liquid pressure is smaller than the reference value, the control unit controls the pumps 52 and 52 'to increase the liquid supply pressure. Thereby, the liquid pressure in the actuator 26 can be set to a predetermined value, and the discharge speed of the liquid droplets discharged from the nozzle and the meniscus of the liquid in the nozzle can be made constant.

  In the present embodiment, since the pressure buffer 1 is installed in the immediate vicinity of the actuator 26, even when the apparatus is increased in size and speeded up and the piping 53 becomes longer, the fluctuation of the liquid pressure in the actuator 26 is effectively reduced and the liquid is increased. The pressure fluctuation in the vicinity of the actuator 26 is detected and feedback controlled to the pump 52, so that the liquid pressure in the actuator 26 can be controlled with high accuracy.

DESCRIPTION OF SYMBOLS 1 Pressure buffer 2 Main body part 3 Buffer member, 3a Plate body, 3b Elastic body 4 Recessed part 5 Communication hole 6 Indoor 7 Spring member 10 Detection part, 10a Main body detection part, 10b Detected part 11 Transmitting coil 12 Reception coil 16 Case 17 Cover 20 Liquid ejecting head 50 Liquid ejecting apparatus

Claims (13)

A recess having an upper end opened, and a main body having a communication hole communicating with an external region on the inner surface of the recess,
A buffer member that is bonded to the upper end surface of the recess to close the opening of the recess and relaxes the pressure fluctuation of the liquid filled therein;
A detection unit that detects a relative position change between the buffer member and the main body,
The buffer member has a central portion made of a plate-like body and a peripheral portion made of an elastic body,
The elastic body is a pressure buffer whose cross section is bent in the radial direction.   The pressure buffer according to claim 1, wherein the elastic body has a ring shape surrounding a peripheral portion of the plate-like body.   The pressure buffer according to claim 1, wherein the deflection has a U shape.   The pressure buffer according to any one of claims 1 to 3, wherein the deflection is convex toward the concave portion.   The pressure buffer according to any one of claims 1 to 4, wherein the deflection is convex on the side opposite to the concave portion.   The pressure buffer according to any one of claims 1 to 5, wherein the bending is such that a convex is continuous on the concave side and a convex is continuous on the opposite side of the concave.   The pressure damper according to any one of claims 1 to 6, wherein the plate-like body and the elastic body are made of the same material, and the plate-like body is thicker than the elastic body.   The pressure buffer according to claim 1, wherein the plate-like body is made of a conductive material or a magnetic material.   The pressure shock absorber according to any one of claims 1 to 8, further comprising a spring member having one end engaged with the plate-like body and the other end engaged with the main body.   The pressure buffer according to any one of claims 1 to 9, wherein the detection unit detects the relative position change by detecting an electromotive force based on electromagnetic induction.   The pressure buffer according to claim 10, wherein the detection unit includes a transmission coil that generates magnetic field lines and a reception coil that induces the electromotive force. The pressure buffer according to any one of claims 1 to 11,
A pipe communicating with the communication hole of the pressure buffer;
A liquid ejecting head comprising: an actuator that discharges the liquid flowing in from the pipe. A liquid jet head according to claim 12,
A tank for containing the liquid and supplying the liquid to the pipe;
And a pump that controls the pressure of the liquid based on the relative position change detected by the pressure buffer.

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