Tubes or conduits, guiding slubbing or roving or the like during pneumatic transport thereof, terminate at a box or cabinet which delimits a compartment connected with the suction side of a ventilator. Within the compartment there is provided for each tube an elongate delay space or chamber, through which pass the slubbing while supported by guide elements, whereas the slubbing-transport air flows off into the compartment by means of throughpass openings. Between outfeed or outlet openings, through which the slubbing departs from the box, and the delay spaces or chambers there are provided dam-up spaces through which there does not flow the transport air and into which there also cannot enter any ambient or outside air, since the band-outlet openings are closed by closure elements, typically pairs of rolls acting as sealing elements. The dam-up spaces permit a brief storage of the incoming slubbing or the like. The box has a tiltable cover, by means of which access to the interior of the box is afforded in order to draw-in the slubbing.

The present invention relates to a new and improved construction of apparatus for the pneumatic transport of band-like textile material especially sliver, slubbing or roving, which apparatus is of the type comprising at least one transport tube or conduit having a delivery or outfeed end which is operatively connected in flow communication by means of a compartment with the suction side of a ventilator, there also being provided a textile band-outlet opening, and the compartment contains means for the support of the band-like textile material.
As stated, the transport apparatus of the invention is particularly suitable for handling sliver, slubbing or roving, but generally may be used with most types of band-like textile materials, and therefore these terms used individually or collectively, in any combinations, are intended as being employed in their broader sense to encompass not only sliver, slubbing or roving as such, but other band-like textile materials.
Equipment is known to the art by means of which it is possible to pneumatically transport textile fiber bands, such as slivers, within tubes or conduits. Such equipment, for the most part still in the experimental stage, aims at simplifying the transport of the band-like textile material, for instance slubbing or roving, while reducing the number of manual operations which have to be performed. Typically, the transport of the band-like textile material is for instance between a card and a drafting arrangement. A further purpose of this type of apparatus is, to the extent that the situation requires, avoidance of any intermediate storage of the transport textile material in a can or the like. On the other hand, such equipment also beneficially enables reducing the annoying presence of dust and other contaminants emanating from the fibrous material within the textile machine halls or rooms containing the equipment, in order to thereby, in conjunction with appropriate measures carried out at the textile machine, to also fulfil strict requirements concerning the working conditions and health hazards as pertains to the machine operators.
During the pneumatic transport of slivers and, in particular, slubbing or rovings which typically are moved by the action of a suction air current, the danger exists of damaging or rupturing the slubbing or the like during such time as the transport air is separated from the conveyed band-like textile material. With a heretofore known apparatus of this type the outfeed or delivery end of the transport tube is connected with a compartment. The slubbing is guided in this compartment over a rotating perforated roll or drum and is supported thereon, whereas the suction air flows off through perforations or holes at the durm surface. A second roll or drum which coacts with the first roll or drum supports the slubbing during the subsequent pressure equalization which takes place.
While the state-of-the-art apparatus is capable of preventing damage to the slubbing or the like, its use is limited to equipment where the peripheral velocity of the drums is (at least) equal to the transport velocity of the slubbing. Apart from the foregoing, such type apparatus is afflicted with the drawback of requiring a considerable amount of space by virtue of the support rolls which are needed and, furthermore, there is required a relatively great expenditure in mechanical equipment.

Apparatus for the pneumatic transport of textile band material


Methods and systems for detection of crossflow and quantification of crossflow effects on fluid distribution during multistage injection treatments of hydrocarbon bearing reservoir formations. A low rate injection stage is applied after a main (high rate) fluid injection stage of a multistage injection treatment process. Wellbore temperature measurements can be utilized along with an inversion process to detect any crossflow and quantify its effects on fluid distribution during the main injection stage. After the effects of any detected crossflow on the fluid distribution are quantified, the effectiveness of the multistage injection treatment can be analyzed and any adjustments or modifications to the treatment can be made accordingly.

Oil and gas wells produce oil, gas and/or petroleum byproducts from subterranean hydrocarbon reservoirs. Various methods and systems are utilized to drill wells into such a reservoir and then extract hydrocarbons from the drilled wells. To enhance hydrocarbon production from the reservoir, stimulation treatments are typically applied to improve near wellbore permeability/conductivity in the subterranean reservoir formation. One example of a commonly used stimulation treatment is the acid treatment, in which an acid based fluid mixture is injected into the subterranean reservoir formation to stimulate and increase the production of hydrocarbons from the reservoir. This is commonly referred to as acidizing. One such aqueous acid treatment, referred to as "matrix-acidizing", involves the introduction of an acid into a subterranean reservoir formation under a pressure below the formation fracture pressure so that the acid flows through the pore spaces of the reservoir formation. The acid of the aqueous acid treatment reacts with acid soluble materials contained in the reservoir formation to increase the size of the pore spaces and increase the permeability of the reservoir formation.
Wellbores are often drilled through reservoir formations that include two or more production zones. Such wells are typically completed by placing a casing along the wellbore length and perforating the casing adjacent each such production zone to extract the formation fluids (such as hydrocarbons) into the wellbore. These production zones are sometimes separated from each other by installing a packer between the production zones. During fluid injection, the fluid penetrates these zones. The extent of fluid penetration in each zone depends on the permeability and the reservoir pressures.
Due to heterogeneities in permeability and pressures in the formations surrounding the wellbore, sometimes the fluids flow from one zone into the wellbore and out into another zone. This phenomenon is called wellbore crossflow and is observed in commingled reservoirs. The crossflow can, for example, lead to inadequate fluid placement during scale-squeeze treatments, as well as to partial stimulation of high pressure zones during matrix acidizing. Real-time wellbore temperature measurements are commonly used to monitor fluid distribution during an injection treatment. However, crossflow effects are generally unnoticeable using temperature measurements acquired at high injection rates, as wellbore temperatures are dominated by a high temperature of an injected fluid, and therefore, produced fluids related to crossflow are unable to affect the wellbore temperatures significantly.

Quantification of crossflow effects on fluid distribution during matrix injection treatments


A receiver is set forth that includes a tuner circuit and a converter circuit. The tuner circuit provides an analog signal corresponding to a modulated signal that is received on a selected channel. The converter circuit includes a sample clock that is used to convert the analog signal to a digital signal at a conversion rate corresponding to the frequency of the sample clock. The sample clock is selectable between at least two different clock frequencies.

Receivers are used in a wide range of applications to convert modulated signals into a form that is suitable for other use. For example, frequency modulated (FM) broadcast receivers are used to convert radio frequency (RF) FM modulated signals to audio signals that can be heard by an individual user through, for example, a speaker system or the like. Other receivers may be used to convert modulated signals to, for example, baseband digital signals that may be used as input to a digital processing system. Cellular phones, televisions, cable boxes, DVD players and recorders, VCRs, and the like, each use at least one type of receiver to accomplish their respective functions.
Many receiver types may be implemented as purely analog circuits. However, receiver designs also may be implemented as hybrid systems that employ both analog and digital circuits. Conversion of analog signals to corresponding digital signals at various points in the reception/demodulation processes executed in such receivers takes place at sample clock rates chosen by the receiver designers. A single sample clock rate is used for a given analog-to-digital conversion in the receiver, although the sample clock rates for analog-to-digital conversions that take place in different portions of the receiver may differ. The sample clock rate selected by the designer is often the result of trade-offs between interference introduced by the analog-to-digital conversion at the sample clock rate and other receiver parameters, such as power consumption, etc. Such trade-offs typically result in a sample clock rate that is not truly optimal for the receiver design. Accordingly, an improvement in the analog-to-digital conversion process employed in such receivers is desirable.

Receiver employing selectable A/D sample clock frequency


A network communication device which can discard invalid packets at once is obtained. A plurality of cells received from input lines (IN#1-4) are stored in a shared buffer memory (SBM) and a control portion (CTL) manages tags and addresses. Among the received cells stored in the shared buffer memory (SBM), ones corresponding to discarded management data are not identified. Accordingly, virtually, the received cells in the shared buffer memory (SBM) can be discarded at once.

1. Field of the Invention
The present invention relates to network communication devices, such as ATM (Asynchronous Transfer Mode) switches, which discard invalid packets.
2. Description of the Background Art
The network communication devices on a network like the Ethernet switch and the ATM switch handle masses of data (hereinafter referred to as packets) as units. Such network communication devices switch packets through hardware to realize high throughput. The ATM switch is the hardware for switching lines. It is determined by an international recommendation that the ATM switches should handle fixed-length (53-byte) packets. Among the packets, fixed-length packets are called "cells."
FIG. 22 is a diagram showing the concept of an example of a conventional ATM switch 100a. Input lines IN#1-4 and output lines OUT#1-4 are connected to the ATM switch 100a. An input portion 11 is connected to the input lines IN#1-4. An output portion 13 is connected to the output lines OUT#1-4. A line interface 11a, a destination analyzing portion 11b and an in-device interface 11c are provided for each of the input lines IN#1-4. A line interface 13a, a destination adding portion 13b and an in-device interface 13c are provided for each of the output lines OUT#1-4. The input portion 11 receives cells provided with destinations from the input lines IN#1-4. In the input portion 11, data in the cells (cell data) are transferred to the switch portion 12 through the line interface 11a, the destination analyzing portion 11b for analyzing the destinations and adding in-device management information to the cell data, and the in-device interface 11c.
Next, the switch portion 12 outputs the cell data to the in-device interfaces 13c corresponding to the destinations. In the output portion 13, the cells are transferred to the target lines through the in-device interface 13c, the destination adding portion 13b for removing the in-device management information added to the cell data and adding destinations to the cells, and the line interface 13a. Thus, the switch portion 12 transfers the cells received from the plurality of input lines to the output lines corresponding to the destinations.
When a plurality of cells directed to a certain output line are received from a plurality of input lines at the same time, the cell data collide (congestion). To avoid the congestion, first, the switch portion 12 once stores the plurality of cell data received from the plurality of input lines into the built-in buffer memory BM. The plurality of cell data directed to a certain output line stored in the buffer memory BM are placed in the wait state until that output line is freed. When the output line becomes free, the switch portion 12 outputs the plurality of cell data directed to that output line to the output portion 13.
The ATM switches containing such a buffer memory BM include those called "shared-buffer ATM switches." The shared-buffer ATM switches include that described in the collection of preparatory manuscripts, Masahiko Ishiwaki et al., "Efficient Self-timed Queue Architecture for a shared-buffering ATM Switch", Institute of Electronics, Information and Communication Engineers of Japan, Integrated Circuit Study Group, ICD94-67, June 1994.
A flow of a plurality of cells (a data stream) may become invalid. This is caused by a trouble on the network or in a terminal connected to the network, for example. Such a trouble is caused when a trouble, e.g., a data error, occurs, or when a request from a source party for connecting the line (hereinafter referred to as "a call") is unexpectedly disconnected, or when a data stream with low priority is interrupted due to congestion of cells on the network, for example.
The capability of managing the cell data in the conventional buffer memory BM is limited. The cell data are, mainly, managed only with the destinations. For example, this management cannot identify cell data belonging to an invalidated data stream. Accordingly, the conventional ATM switch 100a cannot discard invalid cells in the switch portion 12, but the input portion 11 and the output portion 13 discard the invalid cells. For example, suppose that discarding information for informing that cells belonging to a particular data stream are discarded was issued outside of the ATM switch 100a and then the ATM switch received the discarding information. Then the input portion 11 of the ATM switch 100a discards the cells corresponding to the discarding information among the received cells, or the output portion 13 of the ATM switch 100a discards the cells corresponding to the discarding information.
The ATM switch 100a requires high speed performance. Particularly, when a data stream with low priority is interrupted due to congestion of cells on the network, it is preferable to immediately discard the invalid cells. If the cells are not discarded at once, the congestion cannot be avoided.
In the conventional ATM switch 100a, however, the switch portion 12 does not discard invalid cells. Accordingly, the invalid cells cannot be discarded while they exist in the buffer memory BM. After the cell discarding information has been received, the invalid cells are discarded when the corresponding output line has become free and the switch portion 12 has outputted the invalid cells directed to that output line into the output portion 13. Thus, the conventional ATM switch 100a has the problem that even if invalid cells are accumulated in the buffer memory BM, they cannot be discarded at once.


A power supply system of a high reliability and stability capable of suppressing a cross current flow by establishing rapidly synchronism between a power converter and an AC power source in a parallel operation for changing over the power supply sources. The power supply system comprises a current sensor for detecting an AC current supplied from a power converter, a comparator for making decision as to whether the AC current exceeds a predetermined value, and a regulation input means for fetching an active component of the AC power supplied from the power converter in response to an output signal of the comparator, wherein when the AC current exceeds a predetermined value, an output frequency of the power converter is speedily regulated so as to coincide with an output frequency of the AC power source in accordance with a drooping characteristic of the active component of the AC power, while in an isolated operation of the power converter, the output frequency is set at a predetermined value.

1. Field of the Invention
The present invention relates generally to an electric power supply system in which a power converter such as an inverter or the like and other AC power as an electric generator can be operated in parallel by maintaining a current-balanced state. More particularly, the invention is concerned with an electric power supply system in which a power converter such as an inverter and an AC power source such as a generator can be changed over with each other without involving interruption of power supply to a load by suppressing a voltage build-up due to a cross current.
2. Description of the Related Art
A method of operating in parallel a power converter such as an inverter and another AC power source such as a generator by imparting a drooping characteristic to an output frequency of the inverter is well known in the art.
The power supply system of this type is employed, for example, as a static-type power source system for an aircraft. More specifically, during an ordinary flight operation, an onboard electric generator is used as a power source for supplying electric power to a load, while after the landing, operation of the onboard generator is stopped and the power supply to the load is changed over to an inverter installed on the ground. At that time, two power sources are temporarily connected in parallel to the load, whereon these power sources are changed over without interrupting the power supply to the load.
For a better understanding of the present invention, a power supply system of this type known heretofore will be discussed in some detail. FIG. 8 is a block diagram showing schematically a structure of a hitherto known power supply system which includes a power converter connected such that it can be operated in parallel with a generator. Parenthetically, this type power supply system is disclosed, for example, in Japanese Patent Publication No. 24690/1976.
Referring to the figure, a power converter typified by an inverter 1 serves to convert a DC power P.sub.d (a product of a DC voltage V.sub.d and a DC current I.sub.d) supplied from a DC power source (not shown) to an AC power P.sub.1 (a product of an AC voltage V.sub.1 and an AC current I.sub.1). Another AC power source such as an electric generator 2 is provided in parallel to the inverter 1.
The output frequency (frequency of the AC power P.sub.1) of the inverter 1 is controlled or regulated in dependence on the voltage by an inverter control circuit described hereinafter so as to be substantially equal to that of the output frequency of the AC power source 2 (i.e., the frequency of the AC power P.sub.2).
The inverter 1 and the AC power source 2 which constitute a parallel-type power source are connected to an AC bus 5 via switches 3 and 4, respectively. Further, a load 6 is connected to the bus 5 so that the AC power P.sub.1 or P.sub.2 generated by the inverter 1 or the AC power source 2 can be supplied to the load 6. In the parallel operation, both the switches 3 and 4 are closed, and thus the inverter 1 and the AC power source 2 share the power supply to the load 6 with each other. In the ordinary or normal operation, either one of the switch 3 or switch 4 is closed, whereby either one of the inverter 1 or the AC power source 2 bears the power supply to the load 6.
An inverter control circuit for adjusting or regulating the output frequency of the inverter in accordance with an effective or active component of the AC power P.sub.1 is comprised of a voltage control circuit 10 for controlling the AC voltage V.sub.1 supplied from the inverter 1 so that it coincides with a reference voltage V.sub.ref, a subtractor 11 for determining arithmetically a deviation or difference .DELTA.V between the AC voltage V.sub.1 and the reference voltage V.sub.ref, and a voltage sensor 12 for detecting the AC voltage V.sub.1, wherein the elements mentioned above constitute a feedback control circuit for equalizing the AC voltage V.sub.1 outputted from the inverter 1 to the reference voltage V.sub.ref.
The reference voltage V.sub.ref is generated by a reference voltage generating circuit 13 which serves for determining the output frequency of the inverter 1 on the basis of an oscillation frequency f outputted from a voltage-controlled oscillator 14.
The effective power P of the AC power P.sub.1 output from the inverter 1 is detected by a power sensor 15, wherein the effective power P as detected is input to the voltage-controlled oscillator 14.
The voltage-controlled oscillator 14 exhibits a voltage-versus-frequency (P-f) relationship as represented by a solid line curve shown in FIG. 9. Incidentally, a broken line curve represents a power-versus-frequency (P-f) relationship of the AC power source 2 or generator.
The output frequency f of the voltage-controlled oscillator 14 lies at a center frequency f.sub.0 when the inverter 1 is in the no-load state (i.e., when P=0). However, this output frequency f droops as the effective power P increases. By way of example, when the effective power P output from the inverter i increases to P.sub.1 (>0), the oscillation frequency f droops by .DELTA.f. On the contrary, when the effective power P is negative, i.e., when the AC power P.sub.2 is not consumed by the load 6 but fed back as a regenerative power, the oscillation frequency f rises.
FIG. 10 is a block diagram showing an exemplary configuration of the voltage-controlled oscillator 14 exhibiting the operation characteristics illustrated in FIG. 9.
As can be seen from this figure, the voltage-controlled oscillator 14 is comprised of oscillation circuitry 21 including a quartz oscillator which oscillates at a constant frequency F, frequency divider circuitry 22 for dividing the oscillation frequency of the oscillator circuitry 21 to thereby output, for example, an eight-bit signal 22a, an analogue-to-digital (A/D) converter 23 for converting an analogue signal output from the power sensor 15, i.e., the effective power P, into a digital signal such as, for example, a four-bit signal 23a.
The four-bit signal 23a and the eight-bit signal 22a are input to a digital multiplier 24 which serves to modulate the four less significant bits of the eight-bit signal 22a with the four-bit signal 23a to thereby regulate the constant oscillation frequency F in dependence on the effective power P. The output of the multiplier 24 is supplied to a frequency divider 25 which serves for dividing the frequency output of the multiplier 24 to thereby output a proper oscillation frequency f which corresponds to the output frequency of the inverter 1.
Next, referring to FIG. 9, description will be directed to operation of the known power supply system shown in FIG. 8.
It is first assumed that the switch 3 is closed with the switch 4 being opened. In this case, the output power P.sub.1 of the inverter 1 is supplied to the load 6 as a load power P.sub..delta.. Starting from this state, it is again assumed that the power supply to the load 6 is to be changed over from the inverter 1 to the AC power source 2.
For realizing the change-over of the power sources mentioned above without interrupting the power supply to the load 6 through the bus 5, the switch 4 is first closed to establish a parallel operation state in which the invertor 1 and the power source 2 are operated in parallel. Thereafter, the switch 3 is opened. In the parallel operation state, a cross current will flow between the inverter 1 and the AC power source 2, which current has a magnitude corresponding to differences between the output voltages and phases of the inverter 1 and the AC power source 2.
In this conjunction, let's assume that the voltage amplitudes of the output powers of the inverter and the AC power source 2 are equal to each other and that impedance of the inverter and the AC power source connected in parallel is provided only by reactance due to an internal reactance of the electric generator constituting the AC power source. On these assumptions, the cross current may be considered to be provided only by the active current component which is ascribable to the difference in phase between the output of the inverter and that of the power source, Consequently, in the parallel operation of the power supply system, the burden for power supply to the load is shared between the inverter and the power source or generator in dependence on the power-versus-frequency characteristics thereof.
In other words, the power supply system operates at such an operation point where the inverter 1 bears the supply of the power P.sub.1 with the power source bearing the power P.sub.2 at a frequency f.sub.1 shown in FIG. 9. Of course, the load power P.sub..delta. supplied to the load 6 is given by P.sub..delta. =P.sub.1 +P.sub.2.
As can be understood from the above description, by imparting the frequency-versus-characteristic such as mentioned above to the inverter 1 by providing the inverter control circuit constituted by the circuit elements 10 to 15 shown in FIG. 8, the inverter 1 and the AC power source 2 can share the power supply to the load 6 in accordance with the respective power-frequency characteristics.
However, in the known power supply system described above, no consideration is paid to the transient operation state which prevails immediately after the parallel operation has been validated by closing both the switches 3 and 4. Consequently, there arise various problems during a period in which no synchronism is established between the AC powers P.sub.1 and P.sub.2 of the two power sources, i.e., the inverter 1 and the AC power source or generator 2.
With the scheme of the known parallel operation control for the power supply system as described above, the power supply to the load 6 can certainly be shared by the inverter or power converter 1 and the power source 2 in the steady operation state. However, in the transient state, immediately after the system has entered the parallel operation, a large cross current will flow until synchronism is established between the two power sources 1 and 2. Accordingly, in-the system where the inverter 1 and the AC power source 2 are to be changed over without interrupting the power supply to the load 6, the inverter 1 and the AC power 2 are operated in parallel only for a short time. However, in case a large cross current flow which exceeds the rated current of the inverter 1 or the AC power 2 occurs during the parallel operation, the AC voltage V.sub.1 or V.sub.2 of the inverter 1 or the AC power source 2 droops, as a result of which the voltage of the AC bus 5 is lowered during the change-over period or immediately after the lapse of that period, giving rise to a problem that reliability of the power supply system is degraded. Additionally, even in the isolated operation succeeding to the change-over through the parallel operation, the output frequency of the inverter 1 droops in dependence on the effective power P, which in turn means that the output frequency decreases in dependence on the load 6, to another disadvantage.
Furthermore, when the phase of the AC voltage V.sub.2 of the AC power source 2 lags that of the AC voltage V.sub.1 of the inverter 1 upon entering the parallel operation, the AC power P.sub.2 from the AC power source 2 will be transferred toward the AC output terminals of the inverter 1. Consequently, an AC power P.sub.2 is regenerated at the DC input terminals of the inverter 1, resulting in that the DC voltage V.sub.d rises up, whereby there arises the possibility of the elements constituting the inverter 1 being damaged, to a further disadvantage.
It should be noted out that because the effective power P is detected by the power sensor 15, as shown in FIG. 8, the structure of the feedback control system becomes complicated, providing another cause for the deterioration of the reliability of the power supply system.

Electric power supply system using multiple power sources


A flatware separating apparatus comprising a track having a top surface for receiving and delivering different items of flatware along a selected path; a mechanism for contacting selected items of the flatware at a selected point along the path of the track and pushing the selected items off the surface of the track and allowing other selected items of the flatware to remain on the surface; and a mechanism for further separating the selected items of flatware pushed off the surface of the track.

The present invention relates to systems for separating different items of flatware and particularly to automated systems which can receive a plurality of different individual items of flatware, e.g. forks, knives and spoons, and automatically separate the different items into separated collections of the same items. Existing systems for separating one item of flatware from another item, such as a type ACS sorting apparatus available from Erres Storkok, Grums, Sweden, typically include complex mechanisms for identifying a particular individual item of flatware first, e.g. by shape, weight, size, dimension or the like, and then manipulating the item based on its pre-identification in such a way as to separate it from other differently identified items.
The apparatus of the invention is particularly useful in conjunction with a flatware cleaning apparatus which is used in a restaurant or cafeteria operation to constantly clean large numbers of soiled flatware items en masse. In such operations the cleaned collection of flatware must be quickly separated for relatively immediate re use


An active matrix liquid crystal device is provided with improved external terminal structures including an ITO (indiumtin-oxide) pad covering an interconnection wiring, and a layout of a passivation film for protecting an aluminium wiring from outer moisture.

1. Field of the Invention
The present invention relates to thin-film circuit devices, particularly to active matrix liquid crystal display devices with thin-film transistors (TFTs).
2. Description of Prior Arts
Active matrix liquid crystal displays using TFTs as switching elements at each picture-cell (pixel) are disclosed in, for example, pp. 193 to 200 of NIKKEI ELECTRONICS published on Dec. 15, 1986 by Nikkei McGraw-Hill Co. Ltd.

Multi-layer external terminals of liquid crystal displays with thin-film transistors


An object is to provide an ink jet head 1 in which dielectric breakdown does not occur even when a defective portion has occurred in a thin film piezoelectric element 18. After a separate electrode 19, the piezoelectric element 18 and a common electrode 17 are sequentially deposited on a substrate, a minute pulse voltage having a larger voltage value and a shorter application duration than a normal application voltage, which is applied for discharging ink, is applied between the separate electrode 19 and the common electrode 17. A discontinuity portion 25 of the common electrode 17 removed by minute dielectric breakdown is covered by an insulative layer 22. A defective portion 24 of the piezoelectric element 18 becomes a no-voltage-application portion where the applied voltage is locally absent.

The present invention relates to an ink jet head, a method for producing an ink jet head, and an ink jet type recording apparatus.
In the prior art, ink jet type recording apparatuses for recording information by utilizing a piezoelectric effect of a piezoelectric element have been used as printers, word processors, facsimiles, and the like. Typically, an ink jet head for use in a recording apparatus of this type includes a plurality of pressure chambers containing ink, a plurality of nozzles communicated to the pressure chambers, respectively, and an actuator for applying a pressure on the ink in the pressure chamber so as to discharge ink through the nozzle. Some of such actuators are made of a large number of thin films layered together, as illustrated in FIG. 26, for example.
In an ink jet head as described above, a head body 101 is provided with a plurality of pressure chamber depressions 102 arranged in the direction indicated by X1 in the figure. A vibration plate 104 is provided on the head body 101 so as to cover the plurality of pressure chamber depressions 102, so that the vibration plate 104 and the pressure chamber depression 102 of the head body 101 define a pressure chamber 103, A piezoelectric element 105 made of PZT is provided on the vibration plate 104 so as to correspond to each pressure chamber 103, and a separate electrode 106 made of Pt (platinum) is provided on the piezoelectric element 105. Note that the vibration plate 104 is made of Cr (chromium) and functions also as a common electrode of the piezoelectric element 105. The vibration plate 104, the piezoelectric element 105 and the separate electrode 106 together form an actuator. When discharging ink, a voltage is applied between the separate electrode 106 and the vibration plate 104 as a common electrode so as to expand/contract the piezoelectric element 105. Thus, the vibration plate 104 fixed to the piezoelectric element 105 undergoes flexural deformation so as to pressurize the ink in the pressure chamber 103, thereby discharging the ink through a nozzle (not shown).
In recent years, the thickness of the piezoelectric element 105 has been reduced as the ink jet heads have been downsized. However, as the thickness of the piezoelectric element 105 is reduced, the voltage endurance is reduced. Thus, the reduction in the thickness increases the possibility of dielectric breakdown occurring upon application of a voltage. Dielectric breakdown occurring in the piezoelectric element 105 not only reduces the ink discharging performance, but may also leads to leakage of the ink in the pressure chamber 103 to the outside if the degree of dielectric breakdown is high. In view of this, a technique for preventing dielectric breakdown of the piezoelectric element 105 has been longed for in order to improve the reliability of the ink jet head.
As one of such techniques, there is a technique of improving the voltage endurance of the piezoelectric element itself by modifying the crystal structure of a piezoelectric material, as disclosed in Japanese Laid-Open Patent Publication No. 10-217458.
However, during the formation of the piezoelectric element in the process of producing an ink jet head, a defective portion 107 may occur in the piezoelectric element 105 as illustrated in FIG. 27 due to impurities in the production apparatus being introduced into the piezoelectric element or due to the influence of the thermal stress of the piezoelectric element. Therefore, even when the voltage endurance of the material of the piezoelectric element 105 itself is high, the presence of such a defective portion 107 makes the piezoelectric element 105 structurally liable to dielectric breakdown. Specifically, in a case where the defective portion 107 is conductive (e.g., where conductive impurities are introduced), the portion of the piezoelectric element 105 corresponding to the defective portion 107 becomes a portion with a locally reduced thickness, thereby significantly reducing the voltage endurance. Moreover, even in a case where the defective portion 107 is insulative, the piezoelectric element 105 has a non-uniform thickness at the defective portion 107, whereby an electric field localization is likely to occur upon application of a voltage. Therefore, dielectric breakdown is likely to occur in this portion. Particularly, as the thickness of the piezoelectric element is more reduced, the proportion of the defective portion with respect to the piezoelectric element increases. Therefore, the possibility of dielectric breakdown in the piezoelectric element becomes even higher as the thickness of the piezoelectric element is reduced.
Thus, a new technique of preventing the dielectric breakdown of the piezoelectric element in view of the defect which may occur during the formation of the piezoelectric element has been longed for. Moreover, in order to prevent the dielectric breakdown of the piezoelectric element, a new technique of detecting a defect in the piezoelectric element and a new technique of improving the voltage endurance of the piezoelectric element have been longed for.
The present invention has been made in view of the above, and has an object to provide an ink jet head, an ink jet type recording apparatus and a method for producing the same in which the voltage endurance of the piezoelectric element is not reduced even when a defect is included therein.
Moreover, another object is to provide a method for producing an ink jet head in which a defect in the piezoelectric element is detected by a simple method so as to improve the voltage endurance of the piezoelectric element based on the detection. Moreover, another object is to provide an ink jet head and an ink jet type recording apparatus in which the piezoelectric element has a high voltage endurance.
In one embodiment of the present invention, a portion of an upper electrode or a lower electrode corresponding to a defective portion of a piezoelectric element is removed by dielectric breakdown so that an applied voltage is locally absent in the defective portion of the piezoelectric element.
In another embodiment of the present invention, a voltage is applied between an upper electrode and a lower electrode, and a defective portion is detected based on the temperature distribution of the upper electrode or the lower electrode.
In another embodiment of the present invention, a voltage is applied between an upper electrode and a lower electrode to cause minute dielectric breakdown, and a dielectric breakdown portion thereof is detected so as to detect a defective portion.
Specifically, an ink jet head production method according to the present invention is a method for producing an ink jet head for discharging ink by a piezoelectric effect of a piezoelectric element, the method including: a step of, after the piezoelectric element and an upper electrode and a lower electrode of the piezoelectric element are formed, removing, through dielectric breakdown, a portion of the upper electrode or the lower electrode corresponding to a defective portion of the piezoelectric element.
Thus, a portion of the upper electrode or the lower electrode corresponding to the defective portion of the piezoelectric element is removed, whereby at least one of an upper portion or a lower portion overlying/underlying the defective portion of the piezoelectric element becomes an electrode discontinuity portion where the electrode is locally absent. Accordingly, no voltage is applied through the defective portion of the piezoelectric element. Therefore, even if a defect is included in the piezoelectric element, no dielectric breakdown occurs, whereby the voltage endurance of the piezoelectric element does not deteriorate.
The thickness of the piezoelectric element may be 0.5 xcexcm to 5 xcexcm.
Thus, the voltage endurance does not deteriorate even though the piezoelectric element is a thin film, whereby the effect of improving the voltage endurance becomes particularly significant.
Another ink jet head production method according to the present invention is an a method for producing an ink jet head, the ink jet head including: a head body which is provided with a plurality of pressure chambers containing ink and a plurality of nozzles communicated to the pressure chambers, respectively; and a plurality of actuators each having a piezoelectric element and a vibration plate for deforming the vibration plate to apply a pressure on the ink in each of the pressure chambers by a piezoelectric effect of the piezoelectric element so as to discharge the ink through each of the nozzles, the method including: a step of depositing a lower electrode on a first base material; a step of depositing a piezoelectric element on the lower electrode; an upper electrode deposition step of depositing an upper electrode on the piezoelectric element; and a dielectric breakdown step of applying a predetermined voltage between the upper electrode and the lower electrode so as to remove, through dielectric breakdown, a portion of the upper electrode corresponding to a defective portion of the piezoelectric element.
Thus, when a defective portion occurs during the formation of the piezoelectric element, the predetermined voltage applied between the upper electrode and the lower electrode causes minute dielectric breakdown of such a degree that the other portions of the piezoelectric element or the upper electrode are not broken, thereby heating the defective portion or a portion of the upper electrode corresponding to the defective portion, with the heat melting and vaporizing a portion of the upper electrode. Therefore, a portion of the upper electrode corresponding to the defective portion of the piezoelectric element is removed easily and smoothly.
The application of the predetermined voltage in the dielectric breakdown step may be performed after patterning the upper electrode.
Thus, as compared to the case where the predetermined voltage is applied before patterning (separating) the electrode, the area of the electrodes at the time of the voltage application is reduced, whereby the amount of charge stored between the electrodes is reduced. Therefore, the current flowing through the defective portion of the piezoelectric element is reduced, whereby the dielectric breakdown can be easily suppressed to a minute degree. Thus, the minute dielectric breakdown for detecting a defective portion can be easily controlled.
The method may include, after the dielectric breakdown step, a step of embedding an insulator in a removed portion of the upper electrode.
Thus, since the portion where dielectric breakdown has occurred is filled up with an insulator, the application of a normal voltage through the defective portion of the piezoelectric element is reliably prevented. Moreover, ink is prevented from entering the portion from a pressure chamber.
Alternatively, the method may include, after the dielectric breakdown step, a step of covering a removed portion of the upper electrode by an insulator.
Thus, since the portion where dielectric breakdown has occurred is covered by an insulator, the application of a normal voltage through the defective portion of the piezoelectric element is reliably prevented. Moreover, ink is prevented from entering the portion from a pressure chamber.
The method may include, after the dielectric breakdown step: an insulative layer formation step of depositing an insulative layer on the upper electrode; a vibration plate deposition step of depositing a vibration plate on the insulative layer; a step of attaching a second base material, which has been provided with a plurality of pressure chamber depressions and nozzles, to the vibration plate so that the pressure chamber depressions are covered by the vibration plate, whereby a plurality of pressure chambers are defined by the pressure chamber depressions and the vibration plate; a step of removing the first base material; and a step of patterning the lower electrode and the piezoelectric element so as to correspond to the respective pressure chambers.
Thus, the portion where dielectric breakdown has occurred is filled up with an insulator or covered by an insulative layer, as described above, whereby the portion becomes a no-voltage-application portion where the applied normal voltage is locally absent. Therefore, since no voltage is applied through the defective portion, the voltage endurance of the piezoelectric element is maintained. Moreover, ink is prevented from entering the portion from a pressure chamber.
The method may include a step of depositing an insulative vibration plate on the upper electrode, instead of the insulative layer formation step and the vibration plate deposition step.
Thus, an ink jet head in which the vibration plate functions also as an insulative layer is obtained.
The method may include, after the dielectric breakdown step: an insulative layer formation step of depositing an insulative layer on the upper electrode; a vibration plate deposition step of depositing a vibration plate on the insulative layer; a step of providing a plurality of pressure chambers and nozzles in the first base material; and a step of patterning the vibration plate so as to correspond to the respective pressure chambers.
Thus, the portion where dielectric breakdown has occurred is filled up with an insulator or covered by an insulative layer, as described above, whereby the portion becomes a no-voltage-application portion where the applied normal voltage is locally absent. Therefore, since no voltage is applied through the defective portion, the voltage endurance of the piezoelectric element is improved. Moreover, ink is prevented from entering the portion from a pressure chamber.
The method may include a step of depositing an insulative vibration plate on the upper electrode, instead of the insulative layer formation step and the vibration plate deposition step.
Thus, an ink jet head in which the vibration plate function also as an insulative layer is obtained.
When the voltage value of the voltage applied in the dielectric breakdown step is set to be larger than the normal voltage, such a degree of dielectric breakdown that would occur when applying the normal voltage will always occur in the dielectric breakdown step. Conversely, if dielectric breakdown does not occur when applying a voltage larger than the normal voltage, dielectric breakdown will not occur when applying the normal voltage. In view of this, the voltage value of the applied voltage is preferably large. However, when the duration for which the application voltage is applied is excessive, the dielectric breakdown may spread out. Therefore, the duration for which the predetermined voltage is applied is preferably short in order to cause dielectric breakdown only in portions where it is required.
In view of this, the predetermined voltage used in the dielectric breakdown step may be a pulse voltage having a larger voltage value and a shorter application duration than a normal pulse voltage, which is applied for deforming the vibration plate for discharging ink.
Thus, the voltage endurance of the piezoelectric element is highly ensured. Moreover, only a portion of the electrode layer corresponding to the defective portion of the piezoelectric layer is removed smoothly.
The thickness of the upper electrode may be less than or equal to the thickness of the lower electrode.
Thus, it is possible to easily remove only the upper electrode without removing the lower electrode for the portion corresponding to the defective portion of the piezoelectric element, thereby facilitating the subsequent repairing of the removed portion.
Another ink jet head production method according to the present invention is a method for producing an ink jet head, the ink jet head including: a head body which is provided with a plurality of pressure chambers containing ink and a plurality of nozzles communicated to the pressure chambers, respectively; and a plurality of actuators each having a piezoelectric element and a vibration plate for deforming the vibration plate to apply a pressure on the ink in each of the pressure chambers by a piezoelectric effect of the piezoelectric element so as to discharge the ink through each of the nozzles, the method including: a step of depositing a lower electrode on a first base material; a step of depositing a piezoelectric element on the lower electrode; a step of depositing a conductive vibration plate on the piezoelectric element; a dielectric breakdown step of applying a predetermined voltage between the conductive vibration plate and the lower electrode so as to remove, through dielectric breakdown, a portion of the conductive vibration plate corresponding to a defective portion of the piezoelectric element; a step of depositing an insulative layer on the conductive vibration plate; a step of attaching a second base material, which has been provided with a plurality of pressure chamber depressions and nozzles, to the insulative layer so that the pressure chamber depressions are covered by the insulative layer, whereby a plurality of pressure chambers are defined by the pressure chamber depressions and the insulative layer; a step of removing the first base material; and a step of patterning the lower electrode and the piezoelectric element so as to correspond to the respective pressure chambers.
Thus, since the vibration plate is conductive, the vibration plate functions also as the upper electrode. Therefore, it is no longer necessary to separately provide the vibration plate and the upper electrode. Moreover, the portion where dielectric breakdown has occurred is filled up with an insulator or covered by an insulative layer, as described above, whereby the portion becomes a no-voltage-application portion where the applied normal voltage is locally absent, thus improving the voltage endurance of the piezoelectric element.
The application of the predetermined voltage in the dielectric breakdown step may be performed after patterning the conductive vibration plate.
Thus, as compared to the case where the predetermined voltage is applied before patterning (separating) the electrode, the area of the electrodes at the time of the voltage application is reduced, whereby the amount of charge stored between the electrodes is reduced. Therefore, the current flowing through the defective portion of the piezoelectric element is reduced, whereby the dielectric breakdown can be easily suppressed to a minute degree. Thus, the minute dielectric breakdown for detecting a defective portion can be easily controlled.
Another ink jet head production method according to the present invention is a method for producing an ink jet head, the ink jet head including: a head body which is provided with a plurality of pressure chambers containing ink and a plurality of nozzles communicated to the pressure chambers, respectively; and a plurality of actuators each having a piezoelectric element and a vibration plate for deforming the vibration plate to apply a pressure on the ink in each of the pressure chambers by a piezoelectric effect of the piezoelectric element so as to discharge the ink through each of the nozzles, the method including: a step of depositing a lower electrode on a first base material; a step of depositing a piezoelectric element on the lower electrode; a step of depositing a conductive vibration plate on the piezoelectric element; a dielectric breakdown step of applying a predetermined voltage between the conductive vibration plate and the lower electrode so as to remove, through dielectric breakdown, a portion of the conductive vibration plate corresponding to a defective portion of the piezoelectric element; a step of depositing an insulative layer on the conductive vibration plate; a step of providing a plurality of pressure chambers and nozzles in the first base material; and a step of patterning the conductive vibration plate and the insulative layer so as to correspond to the respective pressure chambers.
Thus, since the vibration plate is conductive, the vibration plate functions also as the upper electrode, as described above. Therefore, it is no longer necessary to separately provide the vibration plate and the upper electrode. Moreover, the portion where dielectric breakdown has occurred is filled up with an insulator or covered by an insulative layer, as described above, whereby the portion becomes a no-voltage-application portion where the applied normal voltage is locally absent, thus improving the voltage endurance of the piezoelectric element.
The application of the predetermined voltage in the dielectric breakdown step may be performed after patterning the conductive vibration plate.
Thus, as compared to the case where the predetermined voltage is applied before patterning (separating) the electrode, the area of the electrodes at the time of the voltage application is reduced, whereby the amount of charge stored between the electrodes is reduced. Therefore, the current flowing through the defective portion of the piezoelectric element is reduced, whereby the dielectric breakdown can be easily suppressed to a minute degree. Thus, the minute dielectric breakdown for detecting a defective portion can be easily controlled.
An ink jet head according to the present invention is an ink jet head for discharging ink by a piezoelectric effect of a piezoelectric element, wherein: a first electrode and a second electrode for applying a voltage through the piezoelectric element are provided respectively on opposite sides of the piezoelectric element; and a discontinuity portion is formed through dielectric breakdown in at least one of the first and second electrodes.
Thus, no voltage is applied through the defective portion of the piezoelectric element, whereby an ink jet head having a piezoelectric element with a desirable voltage endurance is obtained.
An insulator may be embedded in the discontinuity portion of the first or second electrode.
Thus, the discontinuity portion is filled up with an insulator, whereby the application of a normal voltage through the defective portion of the piezoelectric element is reliably prevented.
The discontinuity portion of the first or second electrode may be covered by an insulator.
Thus, the discontinuity portion is covered by an insulator, whereby the application of a normal voltage through the defective portion of the piezoelectric element is reliably prevented.
The thickness of the piezoelectric element may be 0.5 xcexcm to 5 xcexcm.
Thus, the voltage endurance does not deteriorate even though the piezoelectric element is a thin film, whereby the effect of improving the voltage endurance becomes particularly significant.
Another ink jet head according to the present invention is an ink jet head ink jet head for discharging ink by a piezoelectric effect of a piezoelectric element, wherein: a first electrode and a second electrode for applying a voltage through the piezoelectric element are provided respectively on opposite sides of the piezoelectric element; a thickness of the first electrode is less than or equal to a thickness of the second electrode; and a discontinuity portion is formed through dielectric breakdown in the first electrode.
Thus, no voltage is applied through the defective portion of the piezoelectric element, whereby an ink jet head having a piezoelectric element with a desirable voltage endurance is obtained.
The thickness of the piezoelectric element may be 0.5 xcexcm to 5 xcexcm.
Thus, the voltage endurance does not deteriorate even though the piezoelectric element is a thin film, whereby the effect of improving the voltage endurance becomes particularly significant.
Another ink jet head production method according to the present invention is a method for producing an ink jet head for discharging ink by a piezoelectric effect of a piezoelectric element, the method including: a step of, after the piezoelectric element and an upper electrode and a lower electrode of the piezoelectric element are formed, detecting a temperature distribution of at least one of the upper electrode and the lower electrode while applying a predetermined voltage between the upper electrode and the lower electrode so as to detect a defective portion of the piezoelectric element based on the temperature distribution.
Thus, when a voltage is applied between the upper electrode and the lower electrode, if a defect is included in the piezoelectric element, minute dielectric breakdown occurs in the defective portion, thereby heating the piezoelectric element. Therefore, it is possible to find the defective portion of the piezoelectric element by detecting the portion whose temperature takes an extreme value (the maximum value or the minimum value).
The temperature of the upper electrode or the lower electrode may be measured by temperature detection means for periodically detecting a temperature; and a plurality of pulse voltages may be applied, as the predetermined voltage, at a cycle less than or equal to the detection cycle of the temperature detection means.
Thus, when a plurality of pulse voltages are applied as the predetermined voltage, unlike the case where a constant voltage is applied for a long time, excessive heating of the upper electrode or the lower electrode is prevented. Moreover, when the cycle of the plurality of pulse voltages is excessively long, the temperature distribution created by the voltage application is leveled out, thereby making the detection of the defective portion difficult. However, according to the above, the cycle of the pulse voltages is less than or equal to the detection cycle of the temperature detection means, whereby it is easy to detect the defective portion.
Each of the pulse voltages may be a pulse voltage having a larger voltage value and a shorter application duration than a normal pulse voltage, which is applied for discharging ink.
Thus, when the voltage value of the pulse voltages is set to be larger than voltage value of the normal pulse voltage, such a degree of dielectric breakdown that would occur when applying the normal pulse voltage will always occur when applying the pulse voltages. Conversely, if dielectric breakdown does not occur by the application of the pulse voltages, dielectric breakdown will not occur when applying the normal pulse voltage. Therefore, the voltage endurance of the piezoelectric element is highly ensured. Moreover, since the duration for which each pulse voltage is applied is shorter than the duration for which the normal pulse voltage is applied, excessive heating of the upper electrode or the lower electrode is prevented, and breakdown of an electrode due to heating is unlikely to occur.
The temperature of the upper electrode or the lower electrode may be detected by temperature detection means for detecting a temperature by elements each having a predetermined size; and the method may include a step of, after an extreme value element for which the detected temperature is maximum or minimum is identified among a plurality of elements, identifying a peak temperature portion within the extreme value element based on a temperature distribution among a plurality of adjacent elements which are adjacent to the extreme value element.
Thus, first, the temperature distribution of the upper electrode or the lower electrode is detected by the temperature detection means having a predetermined resolution in the unit of elements according to the resolution. Then, the temperature of each of the plurality of elements is detected, and the element for which the detected temperature is higher than that of any of the adjacent elements or the element for which the detected temperature is lower than that of any of the adjacent elements is identified as the extreme value element. Then, the temperature distribution within the extreme value element is estimated by interpolation, or the like, based on the temperature distribution among the plurality of adjacent elements which are adjacent to the extreme value element, and a portion where the temperature takes the maximum value or the minimum value within the extreme value element (the peak temperature portion) is identified. Therefore, it is possible to detect the temperature distribution at a resolution equal to or greater than the inherent resolution of the temperature detection means, and to detect a very small defective portion.
The method may include a step of, after a defective portion of the piezoelectric element is detected, removing a portion of the upper electrode or the lower electrode corresponding to the defective portion or a portion of the upper electrode or the lower electrode corresponding to a surrounding portion around the defective portion.
Thus, a portion of the upper electrode or the lower electrode corresponding to the defective portion becomes a discontinuity portion where the electrode is locally absent or an isolated portion which is isolated from the other electrode portions, whereby no voltage is applied through the defective portion of the piezoelectric element during the ink discharging operation. Therefore, dielectric breakdown is unlikely to occur, thereby improving the voltage endurance of the piezoelectric element.
The method may include a step of embedding an insulator in a removed portion of the upper electrode or the lower electrode.
Thus, the portion where dielectric breakdown has occurred is filled up with an insulator, whereby the application of a voltage through the portion is reliably prevented.
The method may include a step of covering a removed portion of the upper electrode or the lower electrode by an insulator.
Thus, the portion where dielectric breakdown has occurred is covered by an insulator, whereby the application of a voltage through the portion is reliably prevented.
The application of the predetermined voltage may be performed after patterning at least one of the upper electrode and the lower electrode.
Thus, as compared to the case where the predetermined voltage is applied before patterning (separating) the electrode, the area of the electrodes at the time of the voltage application is reduced, whereby the amount of charge stored between the electrodes is reduced. Therefore, the current flowing through the defective portion of the piezoelectric element is reduced, whereby the dielectric breakdown can be easily suppressed to a minute degree. Thus, the minute dielectric breakdown for detecting a defective portion can be easily controlled.
Another ink jet head production method according to the present invention is a method for producing an ink jet head for discharging ink by a piezoelectric effect of a piezoelectric element, the method including: a step of, after the piezoelectric element and an upper electrode and a lower electrode of the piezoelectric element are formed, applying a predetermined voltage between the upper electrode and the lower electrode and detecting a dielectric breakdown portion in the upper electrode or the lower electrode which has been created due to the voltage application so as to detect a defective portion of the piezoelectric element.
Thus, when a minute voltage is applied between the upper electrode and the lower electrode, if a defect has occurred in the piezoelectric element, minute dielectric breakdown occurs in the portion. As a result, a portion of the upper electrode or the lower electrode corresponding to the defective portion of the piezoelectric element is scattered away, thereby forming a discontinuity portion in the upper electrode or the lower electrode. Then, the defect of the piezoelectric element is detected by detecting the discontinuity portion with a microscope, or the like.
The method may include a step of, after a defective portion of the piezoelectric element is detected, removing a portion of the upper electrode or the lower electrode corresponding to the defective portion or a portion of the upper electrode or the lower electrode corresponding to a surrounding portion around the defective portion.
Thus, a portion of the upper electrode or the lower electrode corresponding to the defective portion becomes a discontinuity portion where the electrode is locally absent or an isolated portion which is isolated from the other electrode portions, whereby no voltage is applied through the defective portion of the piezoelectric element during the ink discharging operation. Therefore, dielectric breakdown is unlikely to occur, thereby improving the voltage endurance of the piezoelectric element.
The method may include a step of embedding an insulator in a removed portion of the upper electrode or the lower electrode.
Thus, the portion where dielectric breakdown has occurred is filled up with an insulator, whereby the application of a voltage through the portion is reliably prevented.
The method may include a step of covering a removed portion of the upper electrode or the lower electrode by an insulator.
Thus, the portion where dielectric breakdown has occurred is covered by an insulator, whereby the application of a voltage through the portion is reliably prevented.
The application of the predetermined voltage may be performed after patterning at least one of the upper electrode and the lower electrode.
Thus, as compared to the case where the predetermined voltage is applied before patterning (separating) the electrode, the area of the electrodes at the time of the voltage application is reduced, whereby the amount of charge stored between the electrodes is reduced. Therefore, the current flowing through the defective portion of the piezoelectric element is reduced, whereby the dielectric breakdown can be easily suppressed to a minute degree. Thus, the minute dielectric breakdown for detecting a defective portion can be easily controlled.
Another ink jet head according to the present invention is an ink jet head ink jet head for discharging ink by a piezoelectric effect of a piezoelectric element, wherein: a first electrode and a second electrode for applying a voltage through the piezoelectric element are provided respectively on opposite sides of the piezoelectric element; and a discontinuity portion is formed in at least one of the first and second electrodes, the discontinuity portion being provided by removing a portion corresponding to a defective portion of the piezoelectric element or a portion corresponding to a surrounding portion around the defective portion.
Thus, a portion of an electrode on one side or both sides of the piezoelectric element corresponding to the defective portion is removed, whereby an ink jet head having a piezoelectric element with a desirable voltage endurance is obtained.
An insulator may be embedded in a discontinuity portion of the first or second electrode.
Thus, the application of a voltage through the it defective portion of the piezoelectric element is reliably prevented, thereby improving the voltage endurance of the piezoelectric element.
A discontinuity portion of the first or second electrode may covered by an insulator.
Thus, the application of a voltage through the defective portion of the piezoelectric element is reliably prevented, thereby improving the voltage endurance of the piezoelectric element.
An ink jet type recording apparatus according to the present invention includes any of the ink jet head described above.
Thus, a reliable ink jet type recording apparatus having a piezoelectric element with a desirable voltage endurance is obtained.
As described above, according to the present invention, minute dielectric breakdown is caused in a defective portion of a piezoelectric element during the head production process so as to remove beforehand a portion of the upper electrode or the lower electrode overlying/underlying the piezoelectric element corresponding to the defective portion, whereby the defective portion of the piezoelectric element can be a no-voltage-application portion where the applied voltage is locally absent. Therefore, even if a defective portion is included in the piezoelectric element, no voltage is applied through the defective portion during the application of a normal voltage, whereby it is possible to prevent dielectric breakdown from occurring. Therefore, even when the thickness of the piezoelectric element is reduced, the voltage endurance thereof can be desirably maintained.
By filling up the discontinuity portion of the upper electrode or the lower electrode with an insulator, or by covering the discontinuity portion by an insulator, the voltage endurance of the piezoelectric element can be further improved. Moreover, ink is prevented from entering the defective portion.
Moreover, according to the present invention, the defective portion of the piezoelectric element can be easily detected. Therefore, it is possible to increase the voltage endurance of the piezoelectric element by subsequently removing or repairing the defective portion.
With an ink jet head and an ink jet type recording apparatus according to the present invention, no voltage is applied through a defective portion of a piezoelectric element, whereby no dielectric breakdown occurs. Therefore, an ink jet head and an ink jet type recording apparatus having a piezoelectric element with a desirable voltage endurance can be obtained.

Ink jet head, method for manufacturing ink jet head and ink jet recorder

Matsushita Electric Industrial Co., Ltd.


A method produces a composite material using a mixing system. The composite material comprises at least one aggregate, e.g. rock and/or glass, and the reaction product of a two-component polymeric binder composition comprising a first component, e.g. an isocyanate component, and a second component, e.g. an isocyanate-reactive component. The mixing system includes a mixing apparatus. The method includes the step of providing the aggregate, the first component and the second component into the mixing apparatus. The method further includes the step of mixing the first and second components to produce the reaction product of the two-component polymeric binder composition, and the step of applying the reaction product of the two-component polymeric binder composition to the aggregate within the mixing apparatus to produce the composite material. The composite material can be used for forming a paved structure, such as a sidewalk or a roadway.

The use of composite materials to form a paved structure, such as concrete pavement is known in the construction art. Generally, the composite material is produced by mixing at least one aggregate and at least one binder component together. For example, in the case of concrete, the aggregate comprises sand and gravel, and the binder composition comprises cement and water.
Recently, there have been advancements in the use of polymeric materials as the binder composition. Generally, once the aggregate and the binder composition are mixed together, the composite material remains pliable for only a short time, e.g. 45 minutes, before the composite material cures and is no longer pliable. Therefore, such composite materials are typically produced onsite as opposed to offsite. Offsite production requires the composite material to be transported to a construction site thereby decreasing a working time of the composite material once onsite.
Conventional methods of producing the composite material onsite require the aggregate to be placed on the ground before coming into contact with the binder composition. Subsequently, the aggregate is sprayed with the binder composition comprising the polymeric material. A significant drawback of such methods is inconsistent and non-uniform coating of the aggregate, which creates inconsistencies in the composite material. Inconsistencies in the composite material can result in early failure of the composite material thereby requiring the composite material to be replaced at additional cost.
Alternatively, the aggregate and binder composition can be tumbled in a batch mixer for several minutes until the aggregate is uniformly coated with the binder composition before it is set into place. A significant drawback of this process, commonly referred to as a batch process is reduced working time since the binder composition is already starting to react/cure while it is in the batch mixer being tumbled with the aggregate. Also, producing a composite by the batch process limits the efficiency of installing the composite material to form the paved structure.
Accordingly, there remains an opportunity to develop a mixing system that can be employed at a construction site (i.e., employed onsite) on demand that is capable of utilizing recent advancements in polymeric materials as the binder composition thereby providing improved composite materials.

This patent is subject to a terminal disclaimer.

Method of producing a composite material using a mixing system


A cross-linked polymer-supported 4-(N-benzyl-N-methylamino) pyridine material and process for its preparation in high yield and having effective physical and catalytic properties. The polymer supported catalyst is characterized by the suspension copolymerization of an organic phase containing the corresponding vinyl-substituted pyridine monomer, a styrene monomer, and a suitable cross-linking agent and free radical-generating catalyst in the presence of an aqueous phase containing a cellulose ether derivative as the stabilizing agent. A purified acid salt of the vinyl-substituted pyridine monomer useful in polymerizations and stable for storage as either a solid or an aqueous solution.

This invention relates generally to polymer-supported catalysts having pyridylamino functionality, and in particular to a cross-linked copolymer of vinyl-substituted 4-(N-benzyl-N-methylamino)pyridine and a styrene monomer derivative characterized by improved physical properties and marked catalytic activity, and further to an improved acid salt form of the 4-(N-benzyl-N-methylamino)pyridine monomer and the use of the same for preparing polymer-supported catalysts.
By way of general background, it has been recognized for some time that 4-dimethylaminopyridine (commonly referred to as "DMAP") and certain of its dialkylamino analogs are highly effective catalysts for acylations, alkylations and other related reactions. Hofle, G., Steglich, W., Vorbruggen, H., Angew. Chem. Int. Ed. Engl., 17, 569 (1978); Scriven, E. F. V., Chem. Soc. Rev., 129 (1983). Also recognized for some time has been the desirability of a polymer-bound or supported version of such DMAP-like catalysts in view of the potential advantages of ease of recovery and repeated use along with the adaptability of such catalysts in both static and flow systems. Although such polymers could be soluble, it is understood that insoluble, heterogeneous gel or macroreticular resin beads provide the greater advantages in ease of removal and recyclability. Frechet, J. M. J., Deratani, A., Darling, G, Lecavalier, P., Li, N. H., Macromol. Chem. Macromol. Symp., 1, 91 (1986); Patchornik, A., Chemtech, January, 1987, 58.
Accordingly, much investigation has taken place in search of an effective polymer-supported DMAP-like catalyst. For example, Klotz and his coworkers were the first to report such a polymer made by attaching an acid-functionalized dialkylaminopyridine to a polyethyleneimine polymer. Hierl, M. A., Gamson, E. P., Klotz, I. M., J. Am. Chem. Soc., 101, 6020 (1979). Klotz in combination with others subsequently reported similar functionalized polyimines, and demonstrated their catalytic ability by kinetic experiments on the hydrolysis of .rho.-nitrophenyl caproate. Delaney, E. J., Wood, L. E., Klotz., I. M., J. Am. Chem. Soc., 104, 799 (1982); Klotz, I. M., Massil, S. E., Wood, L. E., J. Polymer Sc., Polymer Chem. Ed., 23, 575 (1985). These polymers suffered, however, from the drawback that the pyridine was attached to the polymer backbone by an amide linkage which was susceptible to scission as when regenerating the resin using sodium hydroxide in acetylation reactions involving acyl halides.
Verducci and his coworkers reported attaching 4-piperidinylpyridine, among other DMAP-like moieties, to a Merrifield resin also through an amide bond. Guendouz, F., Jacquier, R., Verducci, J., Tetrahedon Lett., 25, 4521 (1984). The amide bond in this polymer, however, was reported to stand up well on recycle in the catalytic acetylation of 1-methylcyclohexanol at 70.degree. C. and 24 hours.
Nevertheless, more popular approaches to achieve DMAP-like polymer catalysts have avoided the use of amide linkages altogether. For example, Shinkai and his coworkers reported attaching 4-chloropyridine to an aminomethylpolystyrene to yield a polymer-supported 4-(N-benzyl-N-methylamino)pyridine (which functional group has commonly become known as "BMAP"). Shinkai, S., Tsuji, H., Hara, Y., Manabe, O., Bull. Chem. Soc. Jpn., 54, 631 (1981). This polymer-bound BMAP material was reported to effectively catalyze simple esterifications, but the product achieved by Shinkai had the disadvantages of including a high percentage of a secondary amine which interfered with the reaction unless alkylated prior to use.
Another group of investigators led by Tomoi has compared two other approaches to achieve a similar polymeric BMAP catalyst. Tomoi, M., Akada, Y., Kakiuchi, H., Macromol. Chem., Rapid Commun., 3, 537 (1982). Tomoi reported, among other things, that a route involving copolymerization of the preformed BMAP monomer gave a better catalyst product. However, more recently a group led by Frechet challenged this conclusion, reporting that preformed chloromethylated polystyrene can be modified readily and quantitatively to produce an even better catalyst. Frechet, J. M. J., Deratani, A., Darling, G, Lecavalier, P., Li, N. H., Macromol. Chem. Macromol. Symp., 1, 91 (1986). Menger and his coworkers have also reported success in converting a linear chloromethylpolystyrene resin to the corresponding linear BMAP polymer which has proven effective in well-known DMAP-catalyzed processes such as the conversion of linalool to linalyl acetate which has definite commercial interest. Menger, F. M., McCann, D. J., J. Org. Chem. 50, 3928 (1985).
The extent of work in this field has also led groups headed by Frechet, Tomoi, Manecke and Challa to study the effects of variation of the frequency of BMAP-to-styrene units as well as variations of cross-linking and of the length and nature of the spacer arm or component separating the pyridylamino functional group from the polymer backbone. To this end, numerous polymers have been reported by these groups with varying degrees of detail. Deratani, A., Darling, G. D., Horak, D., Frechet, J. M. J., Macromolecules, 20, 767 (1987); Deratani, A., Darling, G. D., Frechet, J. M. J., Polymer 28, 825-830 (1987); 10th Intl. Conf. Heterocycl. Chem. (1985); Tomoi, M., Goto, M., Kakiuchi, H. J., Polym. Sc., Polym. Chem., 25, 77 (1987); Storck, W., Manecke, G., J. Mol. Cat., 30, 145 (1985); and Koning, C. E., Eshuis, J. J. W., Viersen, F. J., Challa, G., Reactive Polym., 4, 293 (1986).
In reviewing these collective efforts, as highlighted above, it is evident that the paramount interest to date has been to confirm the ability to synthesize polymer-supported catalysts of these types approaching DMAP activity. Accordingly, little or no effort has gone into characterizing in a quantitative or qualitative way the physical or chemical properties of the polymer compounds thus far obtained. Nevertheless, these same properties dictate the ultimate commercial utility of such polymeric catalysts in whatever reactions they are used.
For example, while these considerable scientific publications have demonstrated the general or potential utility of polymeric catalysts of this type, nearly all have done so with polymers having low degrees of cross-linking up to only about 2% by weight of the total polymerizable monomer present. These prior art polymers have been reported and proven to be mechanically weak and to exhibit noticeable breakage and disintegration both as formed and during use, particularly with even moderate attempts at recycling. In addition, these polymers have exhibited substantial swelling in excess of 100-200% by volume upon exposure to a solvent which has aggravated breakage upon recapture. This is a definite disadvantage in many commercial processes, for example, where space constraints are important.
Moreover, these polymers prepared according to the literature references contain significant amounts of granular powders; flake or other irregular shapes instead of the predominant bead form that is preferred. Such unwanted particles are mechanically unstable and suitable for use only in stirred-slurry or other reactors where clogging of filters or lines is not a concern and where recycling of the catalyst is not contemplated. The gel-type bead segments that are present in these reference materials are nonuniform in size or configuration, exhibit great deviation from the average or median size present, and do not show the durable, hard form that is preferred. While Frechet has reported making a 34% divinylbenzene (DVB) cross-linked macroreticular resin also within this class, he reported and subsequent testing has confirmed that it has inferior chemical and physical properties as a catalyst in the acylation of 1-methylcyclohexanol. In addition, Frechet's resin made from his preferred chloromethylated polystyrene process may contain quaternary salt from unwanted side reactions which can react to ring-open under strongly basic conditions as often encountered.
Therefore, while certain publications have reported the synthesis of polymer-supported DMAP-like resins and their general catalytic ability, there has been and remains today the need for a catalyst of this type in both gel and macroreticular form that exhibits overall mechanical stability as expected with higher degrees of cross-linking while retaining effective chemical properties believed lost in such materials. Improved physical properties of surface texture and configuration, uniformity and durability are also desired, as are chemical properties approaching the catalytic potency and universal acceptance of DMAP and its analogs.
Further, difficulties in handling the BMAP monomer starting material have been encountered. In particular, BMAP monomer in its free base form is quite reactive. As a monomer related to styrene, BMAP monomer tends to polymerize readily and does not survive manipulations well. For example, even distillation in a falling film still under high vacuum produces very low recovery of BMAP monomer free base. Purification by crystallization is also difficult as BMAP monomer free base is a low melting solid. Consequently, present preparations of polymer-supported 4-(N-benzyl-N-methylamino)pyridine catalysts employ relatively impure BMAP monomer.
In synthesizing the free base, the BMAP monomer according to the references above is generally isolated as a solution of a crude product which may contain a number of useless, even interfering, by-products. Among these may be mineral oil, unreacted vinylbenzyl chloride and 4-methylaminopyridine (MAP). Additional unknown compounds and intractable materials are also present. The presence of these by-products in the BMAP monomer starting material, and the previous inability to effectively purify it, have detracted from the purity of the catalyst product and resultantly from its efficient and effective use.
Also, the polymerizations themselves have been required to be carried out relatively quickly after synthesis of the BMAP monomer due to its reactivity and inherent instability. As a result, preparation of the monomer has been limited to the quantity needed for immediate use as the free base cannot be stored for any appreciable length of time pending further use. Preparation of quantities of monomer exceeding amounts immediately consumable have typically resulted in loss of this excess and waste of the materials.

4-(N-benzyl-N-methylamino)pyridine acid salts and use in preparation of polymer-supported catalysts


A differential envelope detector for detecting the envelope of a received differential signal. The received differential signal comprises first and second received voltages, and the differential envelope detector provides a differential output voltage comprising first and second output voltages, where the difference of the first and second output voltages is indicative of the envelope of the difference of the first and second received voltages. For full-wave rectification, the first received voltage is coupled to the non-inverting input port of a first differential amplifier and the inverting input port of a second differential amplifier, and the second received voltage is coupled to the inverting input port of the first differential amplifier and the non-inverting input port of the second differential amplifier. The output ports of the differential amplifiers are coupled to their input ports to provide negative feedback. The output ports of the differential amplifiers source and sink small-signal current to and from capacitors, where the voltage potential of the capacitors provides the first and second output voltages.

The present invention relates to analog circuits, and more particularly, to envelope detectors.
The Home Phoneline Networking Alliance (HomePNA) is an incorporated, non-profit association of companies working to bring networking technology to the home. See www.homepna.org. HomePNA envisions bringing Ethernet technology to the home by utilizing existing home phone wiring for the network physical medium. HomePNA provides specifications for the physical layer (PHY), its interface to an Ethernet MAC (Media Access Control), and its interface to the home phone wiring. See the IEEE (Institute of Electrical and Electronic Engineers) 802.3 standard for Ethernet.
The position of a HomePNA PHY in relationship to the OSI (Open Systems Interconnection) model is illustrated in FIG. 1. Logical Link Control (LLC) 102 and MAC 104 are implemented in accordance with IEEE 802.3, and HomePNA PHY 106 communicates with MAC 104 via interface 108. Additional sublayers, and other optional layers, may be added to the layers shown in FIG. 1 so that PHY 106 may provide services to other communication protocols, such as Gigabit Ethernet. In practice, PHY 106 and MAC 104 may be integrated on a single die, so that interface 108 is not readily visible.
PHY 106 receives a MAC frame from MAC 104, strips off the 8 octets of preamble and delimiter from the MAC frame, adds a HomePNA PHY header to form a HomePNA PHY frame, and transmits the PHY frame on physical medium 108. A PHY frame is transmitted on physical medium 108 utilizing pulse position modulation (PPM). All PHY symbols transmitted on physical medium 108 comprise a pulse formed of an integer number of cycles of a square wave that has been filtered with a bandpass filter. The position of the pulse conveys the transmitted symbol. Differential signaling is employed, in which a pulse and its negative are transmitted on two wires for each transmitted symbol.
FIG. 2 illustrates an example of received waveforms. Although differential signaling is employed, for simplicity FIG. 2 shows only a single-ended version of the received differential signal. Each symbol is 129 tics long, where 1 tic is defined as (7/60)10xe2x88x926 seconds, which is approximately 116.667 nanoseconds. Pulses are positioned within one of four time slots to convey two bits of information. The time slots are separated by 20 tics, and are at positions 66, 86, 106, and 126 tics from the beginning of a symbol interval. A special SYNC symbol, indicated as AID (Access Identification) symbol 0 in FIG. 2, is composed of a SYNC_START pulse beginning at tic=0 and a SYNC_END pulse beginning at tic=126. In FIG. 2, AID symbol 1 comprises a pulse in position 1 (tic=86), and AID symbol 2 comprises a pulse at position 2 (tic=106). A receiving PHY performs full-wave rectification of the received signals, and compares the envelope of the rectified signals with an AID slice threshold. The PHY detects a received pulse if its envelope exceeds the AID slice threshold. As soon as a pulse is detected by a PHY, the PHY disables further indications of detection until a time AID_END_BLANK (located at tic=61) from the beginning of the pulse, after which detection indication must be re-enabled for the next received pulse.
One approach for detecting the envelope of a differential signal is to form the difference of the received differential signals to provide a single-ended signal, followed by detecting the envelope of the single-ended signal. One such envelope detector is shown in FIG. 3. A single-ended voltage signal V is applied to non-inverting port 302 of differential amplifier 304 and to inverting port 306 of differential amplifier 308. Diodes 310 and 312 provide full-wave rectification, so that capacitor 314 charges when either diode 310 or diode 312 is forward biased. The output voltage Vout at node 316 is proportional to the envelope of the input signal V. Resistor 318 allows capacitor 314 to discharge when there is no received signal.
The present invention improves upon the envelope detector of FIG. 3 for networks employing differential signaling.


A silicon nitride composite sintered which comprises crystal grains of silicon nitride and/or sialon having an average minor axis length of 0.05 to 3 .mu.m and an aspect ratio of 10 or less and foreign particles dispersed in the crystal grains and/or the grain boundary phase, said particles having a thermal expansion coefficient of 5.times.10.sup.-6 /.degree.C. or more and an average particle size of 1 to 500 nm. The sintered body is produced by wet mixing silicon nitride powder, at least two sintering aids selected from among Y.sub.2 O.sub.3, Al.sub.2 O.sub.3, AlN and MgO and at least one compound selected from among the oxides, nitrides, carbides and silicides of the elements, excluding Si and C, of the groups IIa, IIIa, IVa, Va, VIa, IIb, IIIb and IVb of the Periodic Table to form a molding; and heat treating under the specified conditions. The sintered body can also be obtained by coating the surfaces of silicon nitride crystal grains with an organometallic compound convertible to the above foreign particles, heat treating and sintering with the sintering aid.

1. Field of the Invention
The present invention relates to a silicon nitride composite sintered body having high strength and high toughness and a process for producing the composite sintered body, and provides structural ceramic materials to be used for automobile parts, wear-resistant tools, etc.
2. Description of Prior Art
Silicon nitride is a material well-balanced in strength, fracture toughness, and resistances to corrosion, abrasion, thermal impact, oxidation, etc., and has attracted attention recently as an engineering ceramic for structural materials to be used at room temperature and further at elevated temperature. However, in order to put silicon nitride ceramics to use in the field where high reliability and safety are required of the materials of construction such as automobile parts, it is indispensable to further improve the fracture toughness of the ceramics to overcome the brittleness thereof and also to contrive an increase in the strength thereof. There is disclosed, for example, in Japanese Patent Publication No. 265173/1987 a technique for improving the fracture toughness of a ceramic material by combining silicon nitride matrix with silicon carbide whisker to disperse the whisker in the matrix. It is believed that this method can achieve the improvement in the fracture toughness of a ceramic material because the crack which progresses and expands during the fracture is deflected by the whisker, or extraction or crosslinking of the whisker takes place. Although the fracture toughness of the ceramic material is improved by the combination thereof with the whisker, it is substantially difficult to completely remove the agglomerate of the whiskers by mechanical means since the size thereof is of the order of 1 to 10 .mu.m and thus the agglomerate as the coarse grain functions as a breaking point, thereby decreasing the strength of the ceramic material.
According to the conventional methods, therefore, it has been difficult to simultaneously improve the strength and the toughness of silicon nitride ceramics, since the fracture toughness thereof has been improved by the addition of the whisker or by allowing large columnar crystals to exist by grain growth of silicon nitride, which has resulted in substantial expansion of the size of defects and a decrease in the strength thereof. Accordingly, it has been a serious problem how to reconcile the improvement in the strength with that in the toughness of a silicon nitride ceramic having a structure in which the silicon nitride matrix is constituted of fine uniform particles free from coarse grains.

Silicon nitride composite sintered body and process for producing the same