JP2000343696A - Liquid discharge head and liquid discharge recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the discharge of liquid droplets by each of heat generating elements by building a strain gauge into a movable member and reading output voltage detected by the strain gauge using a circuit part. SOLUTION: Strain gauges R1, R2 are installed on the surface layers, of the top plate 3 side and the heater board 1 side, of a movable member 6 consisting of SiN, and these strain gauges R1, R2 comprise the movable member 6 on which a fine resistance wire 200 of polysilicone is formed and a lead wire electrode 201 formed on both ends of the resistance wire 200. In addition, input voltage is applied to a bridge circuit using the resistance wire 200 of polysilicone to read output voltage and thus the distortion level of the movable member 6 itself is measured. Consequently, it is possible to adjust a pulse width and a pulse waveform applied to each of the heat generating elements and stabilize the discharge characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to control of a liquid discharge head and a recording apparatus having the head.

[0002]

2. Description of the Related Art Liquid discharge recording apparatuses, particularly ink jet recording apparatuses, are widely used in modern business offices and other business processing departments.

[0003] A head (referred to as an ink jet recording head) provided in such a recording apparatus includes a plurality of fine holes (orifices) for discharging a recording liquid such as ink, a plurality of liquid flow paths each communicating with each orifice, and a plurality of liquid passages. An ejection energy generating element positioned in the liquid flow path is provided. By applying a drive signal corresponding to the recording information to the ejection energy generation element and applying ejection energy to the recording liquid in the liquid flow path where the ejection energy generation element is located,
The recording liquid is ejected from the orifice as flying droplets to perform recording.

As shown in FIG. 10, for example, this type of ink jet recording head includes an orifice plate 100 having orifices formed with high precision, a top plate 101 having a plurality of liquid flow grooves communicating with the orifices, respectively. S having a plurality of ejection energy generating elements 102 formed on the surface
and an element substrate 103 made of an i-substrate. Orifice 104 of orifice plate 100, top plate 101
And the ejection energy generating elements 102 on the element substrate 103 are positioned so as to correspond to each other, and are joined by an urging means such as a spring or an adhesive.
03 is fixed on the base plate 105 together with a wiring board (not shown) having a pad for receiving an electric signal such as a drive signal from the main body device, which is located at the end of the electric wiring 03

[0005]

Such an ink jet recording apparatus has been developed and studied so as to meet user demands such as formation of a high-definition recorded image and relatively easy maintenance and inspection.

[0006] As a result of earnest studies, the present inventors have provided a movable member in a nozzle and provided a recording apparatus which can meet the above-mentioned demands, and by detecting a strain at the time of displacement of the movable member, the flow rate has been reduced. We have found a new head configuration that can predict the dynamic viscosity of the liquid in the road and adjust the driving conditions of the heating element.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a recording head and a recording apparatus capable of monitoring the dynamic viscosity of liquid in each nozzle and stabilizing the ejection of droplets by each heating element.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a liquid ejecting apparatus comprising a plurality of first liquid passages connected to each of a plurality of discharge ports for discharging liquid. A plurality of energy generating elements arranged in each of the liquid flow paths for generating discharge energy for discharging liquid from the discharge ports in a substrate and a second substrate, and driving conditions of the energy generating elements are controlled. A plurality of elements or electric circuits having different functions, and a liquid ejection head further comprising a movable member in each of the liquid flow paths,
A strain gauge provided in the movable member; and a circuit unit for reading an output voltage detected by the strain gauge.

The energy generating element is an electrothermal converting element.

According to the present invention, there is provided the above-described liquid discharge head, wherein the recording is performed by discharging the liquid to a recording medium by driving the energy generating element while adjusting the energy generating element based on the output voltage obtained by the circuit section. And a liquid discharge recording apparatus.

In the invention described above, since the movable member having the strain gauge is disposed in the liquid flow path, the displacement of the movable member can be electrically measured by a change in the resistance of the strain gauge. In particular, from the amount of distortion of the movable member in the liquid, it is possible to predict the dynamic viscous force of the liquid and the temperature factor which governs the dynamic viscous force. By adjusting, the ejection characteristics can be stabilized.

The terms "upstream" and "downstream" used in the description of the present invention refer to the flow direction of a liquid from a liquid supply source to a discharge port through a bubble generation region (or a movable member), or in terms of this configuration. Is used as an expression for the direction of.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of a liquid discharge head according to an embodiment of the present invention, taken along a liquid flow direction.

As shown in FIG. 1, this liquid discharge head is provided with a plurality of (only one is shown in FIG. 1) heating elements 2 for providing thermal energy for generating bubbles in the liquid. A liquid composed of a substrate 1, a top plate 3 joined on the element substrate 1, an orifice plate 4 joined to the front ends of the element substrate 1 and the top plate 3, and a liquid composed of the element substrate 1 and the top plate 3. It has a movable member 6 installed in the flow path 7 and a strain sensor (not shown) provided on the movable member 6.

The element substrate 1 is formed by depositing a silicon oxide film or a silicon nitride film on a substrate such as silicon for insulation and heat storage, and patterning an electric resistance layer and wiring constituting the heating element 2 thereon. It was done. The heating element 2 generates heat by applying a voltage from the wiring to the electric resistance layer and passing a current through the electric resistance layer.

The top plate 3 constitutes a plurality of liquid channels 7 corresponding to the respective heating elements 2 and a common liquid chamber 8 for supplying a liquid to each of the liquid channels 7. Heating element 2
A channel side wall 9 extending between the two is integrally provided. The top plate 3 is made of a silicon-based material, and a pattern of the liquid flow path 7 and the common liquid chamber 9 is formed by etching, or a silicon nitride, silicon oxide, or the like is formed on a silicon substrate by a known film forming method such as CVD. After depositing the material to be the flow path side wall 9, the liquid flow path 7 can be formed by etching.

The orifice plate 4 has a plurality of discharge ports 5 corresponding to the respective liquid flow paths 7 and communicating with the common liquid chamber 8 via the respective liquid flow paths 7. The orifice plate 4 is also made of a silicon-based material. For example, the orifice plate 4 is formed by shaving the silicon substrate having the discharge ports 5 to a thickness of about 10 to 150 μm. In addition, the orifice plate 4 is not necessarily required for the present invention,
Instead of providing the orifice plate 4, a wall equivalent to the thickness of the orifice plate 4 is left on the tip surface of the top plate 3 when forming the liquid flow path 7 in the top plate 3, and the discharge port 5 is formed in this portion. Thus, a top plate with a discharge port can be provided.

The movable member 6 is provided on the heating element 2 such that the liquid path 7 is divided into a first liquid flow path 7 a communicating with the discharge port 5 and a second liquid flow path 7 b having the heating element 2. It is a cantilever-shaped thin film disposed to face each other, and is formed of a silicon-based material such as silicon nitride or silicon oxide.

The movable member 6 has a fulcrum 6a on the upstream side of a large flow flowing from the common liquid chamber 8 through the movable member 6 to the discharge port 5 by the liquid discharging operation, and has a fulcrum downstream of the fulcrum 6a. The heating element 2 is disposed at a position facing the heating element 2 at a predetermined distance from the heating element 2 so as to cover the heating element 2 so as to have the free end 6b. A space between the heating element 2 and the movable member 6 is a bubble generation area 10.

When the heating element 2 is heated based on the above configuration, heat acts on the liquid in the bubble generation region 10 between the movable member 6 and the heating element 2, thereby causing a film boiling phenomenon on the heating element 2. Based bubbles are generated and grow. The pressure caused by the bubble growth acts on the movable member 6 preferentially, and as shown by the broken line in FIG.
Displace so that it opens greatly to the side. By the displacement or the displaced state of the movable member 6, the propagation of the pressure based on the generation of bubbles and the growth of the bubbles themselves are guided to the ejection port 5 side, and the
The liquid is discharged from.

That is, the liquid flow path 7 is
By providing the movable member 6 having the fulcrum 6a on the upstream side (the common liquid chamber 8 side) and the free end 6b on the downstream side (the discharge port 5 side) of the flow of the liquid in the inside, the pressure propagation direction of the bubble is downstream. And the pressure of the bubbles directly and efficiently contributes to the ejection. Then, the growth direction of the bubble itself is guided in the downstream direction similarly to the pressure propagation direction, and the bubble grows larger downstream than upstream. As described above, by controlling the growth direction itself of the bubble by the movable member and controlling the pressure propagation direction of the bubble, fundamental discharge characteristics such as discharge efficiency, discharge force, and discharge speed can be improved.

On the other hand, when the bubble enters the defoaming step, the bubble rapidly disappears due to a synergistic effect with the elastic force of the movable member 6, and the movable member 6 is finally moved to the initial position shown by the solid line in FIG. Return to. At this time, the liquid flows in from the upstream side, that is, the common liquid chamber 8 side, in order to supplement the contracted volume of the bubbles in the bubble generation region 10 and to supplement the volume of the discharged liquid,
The liquid flow path 7 is filled (refilled) with a liquid, and the liquid is refilled efficiently and rationally and stably with the return operation of the movable member 6.

The liquid ejection head of the present embodiment has circuits and elements for driving the heating element 2 and controlling the driving thereof. These circuits and elements are assigned to the element substrate 1 or the top plate 3 according to their functions. Further, since the element substrate 1 and the top plate 3 are made of a silicon material, these circuits and elements can be easily and finely formed using a semiconductor wafer process technology.

The structure of the element substrate 1 formed by using the semiconductor wafer process technology will be described below.

FIG. 2 shows a liquid discharge head used in the liquid discharge head shown in FIG.
FIG. 2 is a cross-sectional view of an element substrate obtained. As shown in FIG.
In the element substrate 1 used for the liquid ejection head of the embodiment,
Is a thermal acid as a heat storage layer on the surface of the silicon substrate 301.
The oxide film 302 and the interlayer film 303 also serving as a heat storage layer
They are stacked in order. As the interlayer film 303, SiO
_TwoFilm or Si_ThreeN_FourA membrane is used. Interlayer film 303
Resistance layer 304 is formed partially on the surface of
The wiring 305 is partially formed on the surface of the wiring 4. wiring
As 305, Al or Al-Si, Al-Cu
Al alloy wiring is used. This wiring 30
5. The surface of the resistive layer 304 and the interlayer film 303 is coated with SiO
_TwoFilm or Si_ThreeN_FourA protective film 306 made of a film is formed.
ing. The surface of the protective film 306 corresponding to the resistance layer 304
And its surroundings are caused by the heat generated by the resistance layer 304.
To protect the protective film 306 from chemical and physical impact
The anti-cavitation film 307 is formed. resistance
A region where the wiring 305 is not formed on the surface of the layer 304
Is a heat acting portion 3 which is a portion where the heat of the resistance layer 304 acts.
08.

The film on the element substrate 1 is sequentially formed on the surface of a silicon substrate 301 by a semiconductor manufacturing technique, and the silicon substrate 301 is provided with a heat acting portion 308.

FIG. 3 is a schematic cross-sectional view of the element substrate 1 shown in FIG.

As shown in FIG. 3, the N-type well region 422 and the P-type
The mold well region 423 is partially provided. Then, the P-Mos 420 is added to the N-type well region 422 by introducing and diffusing impurities such as ion plating using a general Mos process.
3 is provided with an N-Mos421. P-Mos4
Reference numeral 20 denotes a source region 425 and a drain region 426 in which an N-type or P-type impurity is partially introduced into a surface layer of the N-type well region 422, and an N-type well region 422.
It is composed of a gate wiring 435 and the like deposited on the surface of the portion excluding the source region 425 and the drain region 426 via a gate insulating film 428 having a thickness of several hundreds of mm. The N-Mos 421 includes a source region 425 and a drain region 426 in which an N-type or P-type impurity is partially introduced into the surface layer of the P-type well region 423, and a source region 425 and a P-type well region 423. The gate insulating film 4 having a thickness of several hundred Å is formed on the surface except for the drain region 426.
The gate wiring 435 and the like are deposited via the gate wiring 435. The gate wiring 435 is made of polysilicon having a thickness of 4000 to 5000 nm deposited by the CVD method. These P-Mos420 and NM
The os421 forms a C-Mos logic.

The N-Mos 42 of the P-type well region 423
The portion different from 1 is an N-Mo for driving the electrothermal transducer.
An s transistor 430 is provided. The N-Mos transistor 430 also has a source region 432 and a drain region 431 partially provided in a surface layer of the P-type well region 423 by processes such as impurity introduction and diffusion, and a source region 432 and a drain of the P-type well region 423. The gate wiring 433 and the like are deposited on the surface of the portion excluding the region 431 via the gate insulating film 428.

In this embodiment, the N-mos transistor 430 is used as a transistor for driving the electrothermal transducer. However, the transistor has the ability to drive a plurality of electrothermal transducers individually and has the fine The transistor is not limited to this transistor as long as it can obtain a structure.

Between the P-Mos 420 and the N-Mos 421 and between the N-Mos 421 and the N-Mos transistor 43
5,000 to 10,000 between each element such as between 0 and
An oxide film isolation region 424 is formed by the field oxidation of Å thickness.
Are formed, and each element is separated by the oxide film separation region 424. The portion of the oxide film isolation region 424 corresponding to the heat acting portion 308 plays a role as a first heat storage layer 434 when viewed from the surface side of the silicon substrate 301.

On the surface of each element of the P-Mos 420, the N-Mos 421 and the N-Mos transistor 430,
An interlayer insulating film 436 made of a PSG film or a BPSG film having a thickness of about 7,000 ° is formed by a CVD method. After the interlayer insulating film 436 is planarized by heat treatment,
Wiring is performed by an Al electrode 437 serving as a first wiring layer via a contact hole penetrating the interlayer insulating film 436 and the gate insulating film 428. The surface of the interlayer insulating film 436 and the Al electrode 437 has a thickness of 10,000
An interlayer insulating film 438 made of a 5000 ° SiO ₂ film is formed by a plasma CVD method. Interlayer insulating film 43
8, a portion corresponding to the heat acting portion 308 and the N-Mos transistor 430 has a T
aN _0.8, resistive layer 304 made of _{he x} film is formed by DC sputtering. The resistance layer 304 is formed of the interlayer insulating film 4
Through the through hole formed in the drain region 4
31 and is electrically connected to the Al electrode 437 near. On the surface of the resistance layer 304, an Al wiring 305 is formed as a second wiring layer serving as a wiring to each electrothermal conversion element.

The protective film 306 on the surface of the wiring 305, the resistance layer 304, and the interlayer insulating film 438 is made of a 10000 ° thick Si ₃ N ₄ film formed by a plasma CVD method. The anti-cavitation film 307 formed on the surface of the protective film 306 is made of a film such as Ta having a thickness of about 2500 °.

Next, an example of a step of forming the movable member and the flow path side wall when the movable member 6 and the flow path side wall 9 are provided on the element substrate 1 as shown in FIG. 1 will be described with reference to FIGS. Will be explained. 4 and 5 show cross sections taken along a direction orthogonal to the liquid flow direction of the element substrate on which the movable member and the flow path side wall are formed as shown in FIG.

First, in FIG. 4A, a first pad for protecting a connection pad portion for making an electrical connection with the heating element 2 is provided on the entire surface of the element substrate 1 on the heating element 2 side. As a protective layer, a TiW film (not shown) is formed to a thickness of about 5000 ° by a sputtering method. An Al film for forming the gap forming member 71 is formed to a thickness of about 4 μm on the surface of the element substrate 1 on the side of the heating element 2 by a sputtering method. The formed Al film is patterned by using a well-known photolithography process, and the element substrate 1 and the movable member are positioned at positions corresponding to the bubble generation region 10 between the heating element 2 and the movable member 6 shown in FIG. 6 to form a gap between
A plurality of gap forming members 71 made of a film are formed. Each of the gap forming members 71 is made of SiN which is a material film for forming the movable member 6 in a step of FIG.
The film 72 extends to the region to be etched.

The gap forming member 71 functions as an etching stop layer when the liquid flow path 7 and the movable member 6 are formed by dry etching as described later. this is,
A TiW layer as a pad protection layer on the element substrate 1,
This is because the Ta film as the anti-cavitation film and the SiN film as the protective layer on the resistor are etched by the etching gas used to form the liquid flow path 7, and these layers and films are etched. Is prevented by the gap forming member 71. Therefore, when the liquid flow path 7 is formed by dry etching, the heating element 2 of the element substrate 1 is formed.
The width of each gap forming member 71 in the direction perpendicular to the flow direction of the liquid flow path 7 is adjusted so that the TiW layer on the element substrate 1 and the TiW layer on the element substrate 1 are not exposed. Is wider than the width of the liquid flow path 7 formed by.

Further, at the time of dry etching, CF ₄
Decomposition of the gas generates ionic species and radicals, which may damage the heating element 2 and the functional elements of the element substrate 1. The gap forming member 71 made of Al receives the ionic species and radicals, and This protects the heating element 2 and the functional element.

Next, in FIG. 4B, the gap forming member 71
A SiN film 72 having a thickness of about 4.5 μm, which is a material film for forming the movable member 6 by using a plasma CVD method, on the surface of the element substrate 1 and on the surface of the element substrate 1 on the gap forming member 71 side.
Is formed so as to cover the gap forming member 71.

Next, in FIG. 4C, an Al film having a thickness of about 6100 was formed on the surface of the SiN film 72 by sputtering.
After the formation, the formed Al film is patterned using a well-known photolithography process to form an SiN film 7.
2, a portion corresponding to the movable member 6, ie, SiN
The Al film 73 as a second protective layer is left in the movable member forming region on the surface of the film 72. The Al film 73 becomes a protective layer (etching stop layer) when the liquid flow path 7 is formed by dry etching.

Next, in FIG. 5A, an SN film for forming the channel side wall 9 is formed on the surface of the SiN film 72 and the Al film 73.
The iN film 74 is formed to a thickness of about 50 using a microwave CVD method.
μm is formed. Here, Si by microwave CVD is used.
As a gas used for forming the N film 74, monosilane (SiH ₄ ), nitrogen (N ₂ ), and argon (Ar) were used. In addition to the above,
A combination with disilane (Si ₂ H ₆ ) or ammonia (NH ₃ ) or a mixed gas may be used. Further, the power of the microwave having a frequency of 2.45 [GHz] is set to 1.5 [k].
W] and the gas flow rate is 100 [scc
m], nitrogen 100 sccm, and argon 40 sccm
Then, the respective gases were supplied to form the SiN film 74 under a high vacuum at a pressure of 5 [mTorr]. Alternatively, the SiN film 74 may be formed by a microwave plasma CVD method using a component ratio other than that of the gas, a CVD method using an RF power supply, or the like.

After an Al film is formed on the entire surface of the SiN film 74, the formed Al film is patterned by using a well-known method such as photolithography.
An Al film 75 is formed on the surface of the N film 74 except for a portion corresponding to the liquid flow path 7. As described above, the width of each of the gap forming members 71 in the direction orthogonal to the flow direction of the liquid flow path 7 is wider than the width of the liquid flow path 7 formed in the next step of FIG. Therefore, the side of the Al film 75 is disposed above the side of the gap forming member 71.

Next, in FIG. 5 (b), the SiN film 74 and the S
The iN film 72 is patterned to simultaneously form the channel side wall 9 and the movable member 6. In the etching apparatus, CF
Using a mixed gas of ₄ and O ₂ , using the Al films 73 and 25 and the gap forming member 71 as an etching stop layer or mask, the SiN film 74 has a trench structure.
The N film 74 and the SiN film 72 are etched. In the step of patterning the SiN film 72, unnecessary portions of the SiN film 72 are removed so that the supporting and fixing portion of the movable member 6 is directly fixed to the element substrate 1 as shown in FIG.
The constituent material of the contact portion between the supporting and fixing part of the movable member 6 and the element substrate 1 includes TiW which is a constituent material of the pad protection layer and Ta which is a constituent material of the anti-cavitation film of the element substrate 1.

After that, on the top plate side, which is the other element substrate 3, gold bumps and the like are formed on the surface on which the electrical connection pads are formed, thereby forming a convex electrode portion.

Then, although not shown, bonding using a eutectic metal was performed between the convex electrode on the top plate side and the concave electrode on the element substrate 1 side. At this time, when the same kind of metal is used as the metal species on both sides, the temperature and pressure at the time of joining can be reduced and the joining strength can be increased.

Next, the orifice 5 was formed using an excimer laser through a contact mask provided on the entire face.

Finally, in FIG. 5C, the Al films 73 and 75 are heated and etched using a mixed acid of acetic acid, phosphoric acid, and nitric acid to form the Al films 73 and 75 and the gaps formed of the Al film. The member 71 is eluted and removed, and the movable member 6 and the channel side wall 9 are formed on the element substrate 1. Thereafter, portions of the TiW film as a pad protection layer formed on the element substrate 1 corresponding to the bubble generation region 10 and the pad are removed using hydrogen peroxide. Ti, which is a constituent material of the pad protection layer, is also provided on the contact portion between the element substrate 1 and the channel side wall 9.
W and Ta which is a constituent material of the anti-cavitation film of the element substrate 1 are included. As described above, FIG.
Was manufactured.

FIG. 6 shows an example of a circuit configuration of the element substrate 1 and the element substrate 3 for calculating an output voltage signal detected by a strain sensor provided on the movable member and controlling the energy applied to the heating element. .

In FIG. 6A, on the element substrate 1, heating elements (ejection heaters) 2 arranged in a line, a power transistor 41 functioning as a driver, and an AND for controlling the driving of the power transistor 41 are provided. Circuit 39, a drive timing control logic circuit 38 for controlling the drive timing of the power transistor 41, and the image data transfer circuit 4 including a shift register and a latch circuit.
2 and a rank heater 43 for the discharge heater 2 are formed.

The drive timing control logic circuit 38
In order to reduce the power supply capacity of the device, the heating timing is not supplied to all the heating elements 2 at the same time, but is divided and the heating elements 2 are supplied at different times to supply the power. The enable signal to be driven is input from enable signal input terminals 45k to 45n, which are external contact pads.

The external contact pads provided on the element substrate 31 include an enable signal input terminal 45 k
To 45n, the input terminal 45 of the driving power source of the heating element 2
a, a ground terminal 45b of the power transistor 41, input terminals 45c to 45e for signals required to control energy for driving the heating element 2, a drive power supply terminal 45f of a logic circuit, a ground terminal 45g, and an image data transfer circuit 42 And a serial clock signal input terminal 45h synchronized with the input terminal 45h, and a latch clock signal input terminal 45j input to the latch circuit.

On the other hand, as shown in FIG. 6B, a sensor driving circuit 47 for driving a distortion sensor (not shown) of the movable member 6 is provided in the element substrate 3 which is a top plate. A drive signal control circuit 46 for monitoring the output of the sensor and controlling the applied energy to the heating element 2 in accordance with the result, an output value data detected by the sensor or a code value ranked from the output value, and A memory 49 for storing the liquid discharge amount characteristic (liquid discharge amount at a constant temperature and a predetermined pulse application) of each heating element 2 measured in advance as head information and outputting it to the drive signal control circuit 46 is formed. .

As connection contact pads, terminals 44 for connecting the rank heater 43 for the discharge heater and the sensor drive circuit 47 are provided on the element substrate 31 and the top plate 32.
g, 44h, 48g, and 48h, and terminals 44b to 44d and 48b to connect the drive signal control circuit 46 to input terminals 45c to 45e for signals necessary for controlling the energy for driving the heating element 2 from outside. 48d, a terminal 48a for inputting the output of the drive signal control circuit 46 to one input terminal of the AND circuit 39, and the like are provided.

FIG. 7 shows a structure in which a strain gauge, which is an element for converting the distortion of the movable member 6 into a change in electric resistance, is formed in the movable member. FIG. 7A is a cross-sectional view of one nozzle as viewed along the flow path direction, and FIG. 7B is a plan view of a movable member. As shown in FIG.
Reference numerals 1 and R2 are provided on the surface layer of the movable member 6 on the top plate 3 side and the heater board 1 side, respectively. For example, as shown in FIG. 7B, these strain gauges R1 and R2 form a thin resistive wire 200 of polysilicon on a movable member 6 made of SiN, and form lead electrodes 201 at both ends of the resistive wire 200. It becomes.

Here, the basic principle of this strain gauge is as described below. First, assuming that the length of one bar resistance is L [m] and the cross-sectional area is S [m ² ], the resistivity ρ [Ω ·
m], the total resistance value R [Ω] is R = ρL / S. Here, when the resistor is pulled along with the deformation of the object to be measured, the resistance wire extends. Then, L = L + ΔL becomes longer, and the resistance increases. At this time, the sectional area is also S = S−ΔS
And the resistivity ρ also changes to ρ ′. The relationship between the increase ΔR in the resistance and the increase ΔL in the length is as follows.

R + ΔR = ρ ′ × (L + ΔL) / (S−ΔS) ≒ ρ × L / S + {ρ ′ / (S−ΔS)} × ΔL Therefore, ΔR / R = (ρ ′ / ρ) × ｛S / (S−ΔS)｝ × (ΔL / L) = Kg × (ΔL / L) Here, a constant coefficient K
It is represented by g. The coefficient Kg of the change in resistance with respect to strain is called a gauge factor.

FIG. 8 shows a bridge circuit for converting a resistance change rate into a voltage using the distortion factor.
As shown in FIG. 7 and FIG.
Assuming that the input voltage is 2 [Ω] and the input voltage is E1 [V], the output voltage E
0 [V] is represented by the following equation.

E0 = (R1 × R−R2 × R) / {(R1
+ R) (R2 + R)} × E1 Here, since R1 and R2 employ the same kind of resistance wiring, R1 = R2 = r, and R1 = r +
Δr, R2 = r−Δr. Therefore, E0 = {R × 2Δr / {(R + r) ² −Δr ² }} × E1 Since the amount of strain is a minute strain and the rate of change in resistance is negligible compared to the initial resistance, E0 = {R × 2Δr / (R + r) ² } × E1 Here, when approximating R ≒ r, E0 = (１ ／) × (Δr / r) × E1. In a small change, the output voltage becomes The resistance change is proportional to Δr, and a voltage proportional to the strain (Δr / r) is obtained.

For example, using a polysilicon resistance wire having an initial resistance value of 10 [Ω] and this gauge factor being about 100 and the amount of distortion being 50 [μm], the change Δr in resistance value
Is Δr = 10 [Ω] × 50 × 10 ⁻⁶ × 100 = 50 [mΩ]. When an input voltage E1 = 10 [V] is applied, the output voltage E0 = 25 [mV].

As described above, the amount of distortion of the movable member 6 itself can be measured by detecting the output voltage E0. In particular, the amount of distortion of the movable member in the liquid can predict the dynamic viscous force of the liquid and the temperature factor that governs the dynamic viscous force. By adjusting the pulse waveform etc.
Discharge characteristics can be stabilized.

Further, since the dynamic viscosity of the liquid can be predicted, bubbles and pressure waves generated in the heating element are distributed around the heating element in front of the nozzle (in the direction of the discharge port) and behind the nozzle (in the side of the common liquid chamber). Amount can be detected.
By controlling the pulse width and the pulse waveform applied to the heating element by this distribution amount, stable ejection can always be maintained.

(Other Embodiments) FIG. 9 is a perspective view showing an ink jet recording apparatus which is an example of a liquid discharge recording apparatus to which the above-mentioned ink jet recording head can be mounted. The head cartridge 60 mounted on the ink jet recording apparatus 600 shown in FIG.
1 includes a liquid ejection head having the above-described sensor, and a liquid container for holding a liquid supplied to the liquid ejection head. As shown in FIG. 9, the head cartridge 601 has a carriage 607 that engages with a spiral groove 606 of a lead screw 605 that rotates via driving force transmission gears 603 and 604 in conjunction with forward and reverse rotation of a driving motor 602. Mounted on top. Drive motor 6
By the power of 02, the head cartridge 601 is reciprocated along the carriage 607 along the guide 608 in the directions of arrows a and b. Inkjet recording device 6
00 is provided with a recording medium transport unit (not shown) that transports a print sheet P as a recording medium that receives a liquid such as ink discharged from the head cartridge 601. The platen 6 is moved by the recording medium transport means.
09, a paper holding plate 610 for the printing paper P conveyed on
Presses the print paper P against the platen 609 over the moving direction of the carriage 607.

In the vicinity of one end of the lead screw 605, photocouplers 611 and 612 are provided. The photocouplers 611 and 612 are
07, the photocouplers 611 and 6
This is a home position detecting means for confirming the presence in the area No. 12 and switching the rotation direction of the drive motor 602. In the vicinity of one end of the platen 609, a support member 613 that supports a cap member 614 that covers the front surface of the head cartridge 601 having the discharge port is provided. In addition, an ink suction unit 615 that sucks ink that has been idly discharged from the head cartridge 601 and accumulated inside the cap member 614 is provided. The ink suction unit 615 performs suction recovery of the head cartridge 601 through the opening of the cap member 614.

The ink jet recording apparatus 600 is provided with a main body support 619. The moving member 618 is attached to the main body support 619 in the front-rear direction, that is, the carriage 6.
It is supported so as to be movable in a direction perpendicular to the direction of movement 07. The cleaning blade 617 is attached to the moving member 618. Cleaning blade 6
Reference numeral 17 is not limited to this form, and may be another form of a known cleaning blade. Further, the ink suction means 6
15 is provided with a lever 620 for starting suction in the suction recovery operation by the lever 15. The lever 620 moves with the movement of the cam 621 engaging with the carriage 607, and the driving force from the driving motor 602 switches the clutch. The movement is controlled by a known transmission means such as the like. An ink jet recording control unit for giving a signal to a heating element provided in the head cartridge 601 and controlling the driving of each mechanism described above is provided on the recording apparatus main body side.
It is not shown in FIG.

In the ink jet recording apparatus 600 having the above configuration, the head cartridge 601 reciprocates over the entire width of the print paper P with respect to the print paper P conveyed on the platen 609 by the recording medium conveyance means. Make a record.

[0066]

As described above, according to the present invention, since the movable member having the strain gauge is disposed in the liquid flow path, the displacement of the movable member is electrically measured by the resistance change of the strain gauge. can do. In particular,
From the amount of distortion of the movable member in the liquid, it is possible to predict the dynamic viscous force of the liquid and the temperature factor that governs the dynamic viscous force, thereby adjusting the driving conditions of the energy generating element. Thereby, the ejection characteristics can be stabilized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view along a liquid flow direction for explaining a liquid discharge head structure according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an element substrate used in the liquid discharge head shown in FIG.

FIG. 3 is a schematic cross-sectional view of the element substrate shown in FIG.

FIG. 4 is a view for explaining a method of forming a movable member and a channel side wall on the element substrate shown in FIG. 3;

FIG. 5 is a view for explaining a method for forming a movable member and a flow path side wall on the element substrate shown in FIG. 3;

6A and 6B are diagrams for explaining a circuit configuration of the liquid discharge head shown in FIG. 1, wherein FIG. 6A is a plan view of an element substrate,
FIG. 2B is a plan view of the top plate.

FIG. 7 is a cross-sectional view illustrating a configuration example of a sensor provided in the liquid ejection head of the present invention.

8 is a diagram showing a bridge circuit for converting a rate of change in resistance of a strain gauge, which is the sensor shown in FIG. 7, into a voltage.

FIG. 9 is a schematic perspective view showing an example of a liquid discharge recording apparatus provided with the liquid discharge head of the present invention.

FIG. 10 is a perspective view of a conventional inkjet recording head with a part cut away.

[Explanation of symbols]

 Reference Signs List 1 element substrate 2 heating element 3 top plate 4 orifice plate 5 discharge port 6 movable member 6a fulcrum 6b free end 7 liquid flow path 8 common liquid chamber 9 flow path side wall 10 bubble generation area 71 gap forming member 72, 74 SiN film 73, 75 Al film 200 Polysilicon resistance wire 201 Lead electrode 301 Silicon substrate 302 Thermal oxide film 303 Interlayer film 304 Resistive layer 305 Wiring 306 Protective layer 307 Cavitation resistant film 308 Heat acting part R1, R2 Strain gauge

Continued on the front page (72) Inventor Yoshiyuki Imanaka 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2C057 AF22 AF34 AF93 AG12 AG30 AG46 AG83 AK02 AK07 AK09 AL16 AM15 AP02 AP11 AP32 AP53 BA05 BA13

Claims (3)

[Claims] 1. A liquid is supplied from a discharge port into a first substrate and a second substrate that are joined to each other to form a plurality of liquid flow paths that communicate with each of a plurality of discharge ports that discharge the liquid. A plurality of energy generating elements arranged in each of the liquid flow paths for generating discharge energy to be discharged, and a plurality of elements or electric circuits having different functions for controlling driving conditions of the energy generating elements. The liquid ejection head further comprising a movable member in each of the liquid flow paths, comprising: a strain gauge built in the movable member; and a circuit unit for reading an output voltage detected by the strain gauge. Characteristic liquid discharge head. 2. The liquid discharge head according to claim 1, wherein the energy generation element is an electrothermal conversion element. 3. A liquid ejection head according to claim 1 or 2, wherein the energy generation element is driven based on an output voltage obtained by the circuit unit while being adjusted to eject a liquid to a recording medium to perform recording. A liquid discharge recording apparatus characterized by the above-mentioned.