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United States Patent n 13,590,2s7
[72] Inventors Don A. Berlincourt 3,012,211 12/1961 Mason 333/30 Chagrin Falls; .276.632 9/1966 Malagodi. 310/8.l
Todd R. Sliker, Shaker Heights, both of, 3,363,139 1/1968 Schiauone 3 l0/8.l
Ohio 3.365.590 1/1968 Lobdell 310/8.3
[21] Appl. No. 768,584 3,377,588 4/1968 Pigquendar. 317/235 [22] Filed Sept. 5,1968 3,378,704 4/1968 Miller 310/9 [45] Patented June 29. [971 3,388,002 6/1968 Foster 117/217 [73] Assignee Clevite Corporation 3,398,021 8/1968 Lehrer 1 17/200 Continuation of application Ser. No. 3,399,314 8/1968 Phillips... 3lO/8.6
595,073, Nov. 17, 1966, now abandoned. 3,401,275 9/1968 Curran 310/85 3,422,371 1/1969 Poirier 3 l0/8.2
[54] PIEZOELECTRIC THIN MULTILAYER [56] References Cited UNITED STATES PATENTS 3,433,982 3/1969 Kaname et al. 310/98 X 3,474,268 10/1969 Rudnick 3 10/8.5 3,487,239 12/1969 Schafft 310/85 3,489,931 1/1970 Teaford 310/85 X OTHER REFERENCES lEEE TRANSACTION ON SONlCS AND UL- TRASONlCS, Aug. 1966, Vol. SU13 No. 3 p. 99, article entitled Multilayer Thin Film Piezoelectric Transducers" by John de Kleck Primary ExaminerMilton O. Hirshfield Assistant Examiner-Mark O. Budd Attorney-Frederic B. Schramm ABSTRACT: Alternate thin layers of piezoelectric material having differently orientated piezoelectric axes with respect to each other are placed on a substrater and electroded to form a high frequency resonator. The thickness mode resonant frequency of the composite structure corresponds a proper fraction of the resonator operating frequency, layer thickness varying between 0.2 and 100 microns corresponding to approximately 10 percent of the substrate thickness.
PATENTEU JUN29 I9?! 3690 I 287 sum 1 BF 3 56 INVENTORS 6 DON A.BERLINCOURT TODD R. SLIKER ZZM ATTORNEY PIEZOELECTRIC THIN MULTILAYER COMPOSITE RESONATORS This application is in part a continuation of our copending application Ser. No. 595,073, and now abandoned, filed Nov. 17, I966.
This invention relates to resonant devices and more particularly to such devices employing a plurality of layers of piezoelectric material.
The typical prior art resonator comprises a wafer of piezoelectric material such as quartz or ceramic material provided with electrodes on opposite surfaces thereof. Upon application of an alternating signal, the material between the electrodes is driven electrically in a predetermined vibrational movement, for example, thickness sheer, thickness extensional, and so forth, depending on the orientation or polarization of the wafer material.
The resonant frequency of the resonator is dependent on the overall wafer and electrode thickness and increases with decrease in thickness. At high frequencies very thin wafers are required if fundamental modes are to be used.
Because of difficulties in fabricating extremely thin piezoelectric wafers, prior art high frequency resonators are typically intermediate frequency resonators operated at an odd harmonic of the fundamental frequency. Even harmonics cannot be used since perfect stress cancellation occurs and the electromechanical coupling is zero. At odd harmonics some coupling exists due to imperfect stress cancellation. Even 7 though the odd harmonic coupling is substantially reduced by partial cancellation, in many instances it is of sufficient magnitude to render the resonator suitable for filter applications. For instance, an AT-cut quartz wafer at its fundamental has a coupling factor of about 0.09. At the third, fifth, seventh, and ninth harmonics, couplings of 0.03, 0.0I8, 0.013 and 0.010, respectively are obtained.
In order to achieve greater utility in high frequency applications it has been proposed to deposit a thin film of a suitable material upon a substrate such as a quartz wafer, the thickness of such a film being much less than has heretofore been practical as the thickness of a quartz wafer.
It is an object of the invention to provide improved devices of the type employing layers of piezoelectric material and to form such devices as filters and transformers.
Other objects of the invention are to obtain increased efficiency of conversion in piezoelectric devices, to enable such devices to operate at very high frequencies, to obtain a high frequency selectivity and to provide multiterminal units such as three and four terminal units serving as transformers.
Still another object of the invention is to form composite resonators as multiterminal devices.
In a preferred embodiment of the invention a plurality of layers of material are formed upon a substrate. A sufficient number of surfaces of the layers are electroded so that input terminals may be applied to a pair of electrodes to form a piezoelectric driving element. In order to form a three ter minal or four terminal device which may act as a transformer, one or more additional layers are also electroded at their surfaces. The device may operate at a harmonic of the fundamental frequency of the composite structure but operates generally at a frequency close to that corresponding to a halfwave of the thickness of each layer.
Other objects and advantages will become apparent from the following description taken in conjunction with the accompanying drawings, wherein:
FIG. 1 is a diagram of a three-terminal device employing two thin deposited layers of piezoelectric material upon a substrate with c axes, as in wurtzite crystals, or axes as in sphalerite crystals, perpendicular to the surfaces of the layers and in alignment.
FIG. 2 is a diagram corresponding to FIG. I of a similar device in which the piezoelectric layers are oppositely polarized, that is have their c axes or [III] axes extending in opposite directions.
FIG. 3 is a diagram like that of FIGS. 1 and 2 but for piezoelectric layers with c or [111] axes oblique.
FIG. 4 is a diagram of the type of apparatus illustrated in FIGS. 1, 2, and 3 in which devices are cascaded with a plurality of three-terminal units formed in layers deposited upon the same substrate.
FIG. 5 is a diagram of the three-terminal device in which voltage transformation of a ratio greater than 1 to l is' achieved by the deposition of a plurality of successive layers one upon another employing the same substrate and with electrodes at adjacent surfaces in order to achieve electrical connection between successive active layers.
FIG. 6 is a diagram corresponding to FIG. 5 but employing material so polarized as to have a shear mode of vibration, with alternate layers having c axes tilted at opposite angles so that successive layers may be in direct contact and electroding is unnecessary except where terminals are to be brought out for input and output connections.
FIG. 7 is a fragmentary diagram of devices similar to those illustrated in FIGS. 1 through 6 showing the effect of operation at a frequency which corresponds to an integral number of half-waves in a composite structure but such that the deposited layers each have a thickness differing from one-half wavelength.
FIG. 8 is a diagram of a modified structure in which layers are deposited upon opposite surfaces of a substrate and inequality in stress distribution is balanced.
FIG. 9 is a diagram of a four-terminal device employing piezoelectric layers deposited on opposite surfaces of a substrate.
FIG. 10 is a circuit diagram of an arrangement for further cascading of three-terminal devices to achieve a higher ratio of transformation, FIG. 11 is a diagram of an arrangement for avoiding the need for reversing polarity in multilayer piezoelectric structures.
FIG. 12 is a diagram, with electrodes and connections omitted, of stress distribution on a composite structure driven at the fourth harmonic of the fundamental frequency of the composite structure.
FIG. 13 is a diagram corresponding to FIG. 12 but showing the stress distribution with the composite structure driven at the eighth harmonic ofthe fundamental frequency of the composite structure, with each deposited layer having a thickness corresponding to one-half wave length at the eighth harmonic.
FIG. 14 is a diagram of a composite structure with input and output layers having different thicknesses, and
FIG. 15 is a fragmentary diagram of input layers in the arrangement of FIG. 14.
Like reference characters are utilized throughout the drawings to designate like parts.
Referring to FIG. I of the drawing showing a three-terminal piezoelectric device in accordance with the invention identified generally by the reference numeral 10, the device 10 in general comprises a substrate 12 with two superposed layers 14 and 16 of piezoelectric material deposited thereon. An electrode 18 is interposed between the substrate 12 and the layer or film of piezoelectric material 14. Likewise, an electrode 20 is interposed between the layers 14 and 16, and an electrode 22 is applied to the upper surface of the piezoelectric layer 16. The wafer substrate 12 may be either circular or rectangular in shape. Likewise, the layers 14 and 16 and the electrodes 18, 20, and 22 may be either circular or rectangular in shape. For convenience in production, however, they are preferably circular.
In order that electrical connections may be made to the surfaces of the piezoelectric layers 14 and 16 the electrodes 18 and 22 are connected to terminals 24 and 26, respectively, one being an output terminal and the other being an input terminal. By way of illustration the terminal 24 is shown as an output terminal and the terminal 26 as an input terminal. However, the invention is not limited to this arrangement, as the device is symmetrical, and either terminal may be the output terminal and either terminal the input terminal. In the arrangement illustrated the electrode is common to the ad jacent surfaces of the layers 14 and 16 and common to the input and output circuits having a connection to a third terminal 28 shown as ground.
In the arrangement in FIG. 1 the layers 14 and 16 are composed of piezoelectric material which is polarized perpendicular to its surface, both layers being polarized in the same direction. The piezoelectric axes 30 are perpendicular to the surface of the substrate 12 and extend in the same direction therefrom. The piezoelectric axes referred to in the case of wurtzite type hexagonal crystals are the c axes. The axes are referred to as c axes in such material as cadmium sulfide and cadmium selenide, zinc oxide, beryllium oxide, aluminum nitride wurtzite zinc sulfide and solid solutions thereof. In sphalerite cubic crystals such as zinc sulfide and gallium arsenide, e.g., the piezoelectric axes are the [111] axes. In ferroelectric crystals the ferroelectric axis may usually be identified as the piezoelectric axis. With ferroelectric lithium niobate and lithium tantalate, this terminology is not appropriate, however, and one might rather identify either the ferroelectric axis (Z) or the Y axis as a piezoelectric axis.
However, the invention is not limited to having the piezoelectric axes extend in the same direction. As shown in FIG. 2, for example, one of the layers 14 may be replaced by a layer 14' with its piezoelectric axis III in a direction opposite to the piezoelectric axis 30 of the layer 16.
For clarity in the drawing the electrodes 18, 20, and 22 have been shown relatively thick in comparison with the layers 14 or 14' and 16, which have also been shown relatively thick compared to the substrate 12. In practice, however, the electrodes are generally much thinner than the piezoelectric layers, and the layers are a fraction of substrate thickness. When the layers are deposited upon the substrate 12, the deposite is formed with uniform thickness and the portion of the layer above an electrode merely rises slightly higher than the portion surrounding the electrodes. In order to minimize loss of acoustic energy and to help preserve the energytrapping effect of the portions of the layers 14 and 16 beyond the electrodes 18, 20, and 22, leads 32, 34, and 36 from the electrodes to the terminals 24, 26, and 28 are taken off in different radial directions from the center of the structure. Preferably the leads 32, 34, and 36 are integral with the electrodes 18, 22, and 20 respectively. The actual construction of the electrodes, leads and of the layers 14 and 16, is not a part of the present invention and they may take the form illustrated in the copending application of Daniel R. Curran and Don A. Berlincourt, Ser. No. 542,627, filed Apr. 14, 1966, now Pat. No. 3,40l ,275 assigned to the same assignee as the present application.
The substrate 12, which may be in the form of a wafer, is
preferably formed from a material having a high mechanical Q, and as explained in more detail in the copending application of Curran and Berlincourt may have a frequency temperature coefficient of magnitude and polarity such as to cancel the frequency temperature coefficient of the piezoelectric layers 14 and 16. Suitable materials for the substrate 12 are quart and metallic compositions such as Invar and Elinvar. Other materials which may be employed as substrate are lithium gallate, lithium niobate and lithium tantalate, for instance.
The electrodes 18, 20, and 22 are most conveniently formed by vapor deposition of electrically conductive materials such as gold on chromium or aluminum by one of the numerous techniques known in the prior art. When the electrodes are formed by vapor deposition a mask is placed on the surface of the substrate or previous layer to cover all of the surface except the portion where the electrode is to be formed and the radially extending portion where the lead is to be formed.
When the terminal 26 is employed as the input terminal, the piezoelectric layer 16 serves as the driving element and the piezoelectric layer 14 serves as the driven element together with the substrate 12. Each layer 14 and 16 may be formed by vapor deposition or sputtering of suitable materials which can be oriented during vapor deposition.
As illustrated there are at least two axially distributed films of oriented piezoelectric material on a thin substrate (that is having lateral dimensions large with respect to axial dimensions), with at least one of the films driven electrically at a frequency at or near mechanical resonance of the composite structure, and with the other film or films developing the electrical output.
The substrate provides a mounting upon which to form the piezoelectric layers. It is not driven electrically, serving only as a base for the unit. However, the substrate acts also to raise the overall mechanical Q above that of the piezoelectric material and acts also to exert major control over the frequency-temperature coefficient. The device achieves frequency selection and may achieve either voltage step-up or stepdown (impedance transformation The preferred method of forming the piezoelectric layers 14 and 16 is by vapor deposition of a layer of piezoelectric material on the surface of the wafer 12. As disclosed in copending application Ser. No. 363,369 filed on Apr. 29, 1964, by Lebo R. Shiozawa and assigned to the same assignee as the present invention, material selected from the group consisting of cadmium sulfide, cadmium selenide, zinc oxide, beryllium oxide, wurtzite zinc sulfide and solid solutions thereof as well as aluminum nitride, lithium niobate, and lithium tantalate can be vapor deposited on the surface of a substrate with an orientation such as to produce a thickness extensional mode of vibration.
In the embodiment of FIG. 1, a thickness extensional mode of vibration is employed..Preferably the layers 14 and 16 are deposited on a substrate of quartz. In producing the embodiment of FIG. 2, suitable means are employed for reversing the polarization of the layer 14.
Although the devices of FIGS. 1 and 2 have been described as employing elements having thickness extensional mode of vibration, the invention is not limited thereto; and piezoelectric elements 15 and 17 as shown in FIG. 3 may be employed which have a thickness shear response either with the c axes or [111] axes extending in parallel directions or, as shown in the drawing, tilting in different directions with respect to a line perpendicular to the layer surfaces in adjacent piezoelectric layers. Although structures of the type described could be excited to resonate in a mode of vibration other than the one of the thickness modes of vibration, such as thickness extensional or thickness shear we prefer to use one of the thickness modes. It is in a thickness mode of vibration that advantage is taken of the possibility of depositing very thin layers to obtain the high resonant frequency corresponding to such thin layers.
In the publications Ultra High Frequency CdS Transducer," lEEE Transactions on Sonics and Ultrasonics, Vol. SU-l 1, No.2, pp. 63-68 (1964) by N. F. Foster and Cadmiurn Sulfide Evaporated Layer Transducers, Proc. IEEE, Vol.
53, No. 10, pp. l400-1405 (1965) by NP. Foster a process for vapor depositing cadmium sulfide is disclosed. The latter publication discusses obtaining an orientation to produce a thickness shear mode of vibration. Such prior art techniques are suitable for the formation of layers 15 and 17 shown in FIG. 3.
A preferred combination for the embodiment shown in FIG. 3 comprises a driving and driven elements 17 and 15, respectively, formed by the vapor deposition of cadmium sulfide on a substrate 12 of AT-cut quartz. The cadmium sulfide elements are preferably vapor deposited by a process similar to that disclosed in the N. F. Foster publication with an orientation such as to produce a thickness shear mode of vibration. To achieve optimum temperature stability, AT-cut substrate 12 is slightly off-cut so that the quartz material has a slight positive temperature frequency characteristic which counteracts the larger negative temperature frequency characteristic of the cadmium sulfide material. AT-cut quartz is much preferred because of its temperature stability and very favorable mechanical characteristics.
Because of its high Q and low frequency temperature coefficient, AT-cut quartz is the preferred substrate material and the description will be directed thereto. The before-mew tioned Foster publication disclosed that cadmium sulfide vapor deposited with an angle between the molecular beam and the plane of the substrate has a shear response. We have additionally found that the shear response is optimum when the actual angle between the cadmium sulfide films c axis and the perpendicular to the film surface is between and 40 and maximum at about 30. This is explained more fully in the aforesaid copending application of Curran and Berlincourt.
The devices illustrated in FIGS. 2 and 3 serve as l 1 ratio filter transfonners. They are particularly useful as band pass filters. However, the invention is not limited thereto. They may be connected as step-up auto transformers by connecting the input voltage to the common terminal 28 and either of the other two terminals 24 and 26, and taking the output from terminals 24 and 26.
Such three-terminal devices may also be connected in tandem in compact form to increase the selectivity by mounting several of them upon a single substrate acoustically isolated from each other. FIG. 4 illustrates such an arrangement for two units, although a greater number may be connected in tandem in-the same manner as illustrated in FIG. 4, layers of suitable piezoelectric materials such as cadmium'sulfide l4 and I6 are deposited upon a substrate 12 with two or more sets of electrodes at the successive surfaces of the substrate 12 and the layers 14 and 16. For example, there may be electrodes 18, 20, and 22, with an input terminal 26 connected to the electrode 22, and with the electrode 20 grounded. In addition there is a set of electrodes 38, 40, and 42, corresponding to electrode 18, 20, and 22 deposited upon a different portion of the surface of the substrate 12 and the layers 14 and 16. However, in this case electrode 18 is not connected to an output terminal, but instead to the electrode 38 by means of a lead 44 formedintegral with the electrodes 18 and 38. The electrode 40 is also grounded through a lead 46 connected to electrode 20. The electrode 42 is connected to an output terminal 48 through a lead 50.
The relationship between thicknesses is-preferably such that the structure forms a composite mass loaded multitransformer structure comprising a wafer substrate, a plurality of piezoelectric layers thereon, and electrodes associated with said piezoelectric layers, the effective composite thickness of piezoelectric layers, said electrodes and said substrate defining an electroded region having a resonant frequency, f,,, and the surrounding region of said multitransformer structure defining a resonant frequency,f,,, higher in magnitude than f,,, and the effective composite thickness of the electroded region being such relative to that of surrounding region that ratio 1",, tof is in the range 0.8 to 0.99999. The frequency ratio fl,/f,, is obtained by controlling the thickness of the electrodes or alternatively by selective deposition of a dielectric such as silicon monoxide or silicon dioxide. Dielectric tuning may in addition be used to lower the resonant frequency f,, to its desired value by adjusting the composite element to have an integral number of half wave lengths at the desired frequency.
By suitable connections the devices employing the principles of this invention may also be formed as four-terminal devices instead of three terminal devices with complete direct current electrical isolation between primary and secondary circuits. Moreover, by multiplying layers of piezoelectric material a frequency selective transformer may be formed having a greater ratio of transformation than in the devices previously discussed. For example, as shown in FIG. 5, there is a substrate 12 upon which successive layers 54, 56, 58, 60, 62, 64, 66, and 68 are deposited.
In the arrangement of FIG. 5 films are employed which differ in some respects so that the first and second different types of layers are employed, designated in FIG. 5 as type A layers and type B layers, with different piezoelectric response. The type A layers are piezoelectric and the type B layers are either inactive with respect to piezoelectric properties or also piezoelectric but may differ in some other respect in their piezoelectric properties or response from the type A layers. ln
the specific arrangement illustrated in FIG. 5 the type A layer 68 constitutes the driving element having electrodes with leads 70 and 72 connected to terminals 74 and 76 of a high frequency input source 78. The invention is not limited to a single-layer driving element and does not include arrangements with more than one layer in the driving element or in both driving and driven elements.
The layers 54, 58, 62 and 66 are also type A layers. In order to accomplish a step-up ratio of voltage transformation the layers 54, 58, 62, and -66 are electrically connected in series through leads 80 and 82 to output terminals 84 and 86 respectively. As shown the output terminal 84 is connected to the same electrode as the input terminal 76. However, if complete direct-current electrical isolation between the primary and secondary circuits is desired, the layer 66 may be eliminated and an output connection to an output terminal 88 may be made'from the upper surface of the piezoelectric layer 62, the output terminal 88 then being employed in place of the output terminal 84.
Although the terminals 74 and 76 have been referred to as input terminals, and the terminals 84 and 86 as output terminals, it will be understood that the invention is not limited to a step-up transformation ratio and if desired instead the apparatus may be employed as stepdown frequency selective transformer with the input connected to the terminals 84 and 86 or 88 and 86 and the output taken from the terminals 74 and 76.
- In the arrangement of FIG. 5 the difference between the B- type layers and the A-type layers is assumed to be that the B-' type layers are inactive with respect to piezoelectric properties, or their piezoelectric properties are not utilized. Then in order to connect the A-type layers of secondary circuit in series, metallic films are provided between the A- and B-type layers and the metallic films on either side of each B-type layer are connected so as to provide a direct series connection from one A-type layer to the next. Thus the metallic film or electrode 90 between A and B layers 66 and 64 is connected by a strip 92 to a metallic film or electrode 94 between the B and A layers 64 and 62. Similarly, there is a connection 96 between electrodes 98 and 100 and a strip 102 between electrodes 104 and 106. In the arrangement of FIG. 5, the B-type layers serve to interpose sections of reversed stress so that all A-type layers will be stressed in the same'phase and their voltage outputs will ,be cumulative. If the B layers are metallic, they serve as the connections 92, 96, and 102. To avoid energy loss, improve Q,,,, and avoid decrease in selectivity, the B layers are preferablynot piezoelectric if the connections 92, 96, and 102 are employed.
If it is desired to avoid the use of the shortcircuiting strips 92, 96, and 102, this may be accomplished by making both A and B layers with piezoelectric properties but suitably polarized so that the voltages of successive layers do not cancel out. Thus, if care is taken to make the thickness of each layer A or B one-half wave length for the frequency of the input source 78 so that the state of stress of the A-type layers is opposite to the state of stress of the B-type layers at any instant, then all the A-type layers may be arranged with their 0 axes pointing upward as in layer 16 of FIG. 2 and all the B- type layers may be arranged with their 0 axes pointing downward as in the case of layer 14 of FIG. 2. If this is done the electrodes 90, 94, 98, 100, 104, and 106 may be eliminated. It will be understood of course that electrodes are still required for connection to the terminals 74 and 76 and to terminals 84 and 86 and to the terminal 88 if it is employed.
An arrangement without intervening electrodes or inactive.
layers or metallic deposits is illustrated in FIG. 6. This is accomplished by using A- and B-type layers which have piezoelectric axes such that responses of adjacent layers to thickness shear waves are opposite and the voltages developed across successive layers are additive when one standing acoustic wave length is twice the thickness of one layer.
In FIG. 6 there are four piezoelectric layers 108, 110, 112, and 114 in direct contact with each other with an electrode 116 at the lower end of the stack and an electrode 118 above, connected to the output terminals 86 and 84, respectively. There is likewise a layer 120 resting upon the electrode 118 with an upper electrode 122. The electrical connection to the source 78, having terminals 74 and 76, is made from the electrodes 122 and 118. In the arrangement of FIG. 6 the layers 108, 112, and 120 are A-type layers and the layers 110 and 114 are B-type layers.
FIG. 6 illustrates also the employment of a shear mode of vibration with the c axes 33 of the A-type layers tilted upward to the left and the c axes 35 of the B-type layers pointing upward to the right. FIGS. 5 and 6 both illustrate transformers with a 4 to 1 ratio of transformation. However, as shown by the drawing, the employment of piezoelectric layers which have the c axes differently directed in successive layers enables the employment of a simpler and more compact structure by the elimination of layers such as the B-type layers in FIG. 5 which do not contribute piezoelectrically to the functioning of the apparatus.
It will be understood that the invention is not limited to threeor four-terminal devices and frequency selective transformers of any particular size or power handling capacity. However, by way of illustration the layers of piezoelectric material may consist of evaporated films of cadmium sulfide of the order of 1 micron to 10 microns in thickness. The sub strate 12 may be made of quartz on the order to 100 microns thickness. The metallic layers of electrodes may be on the order of 1,000 to 3,000 Angstroms thick.
The resonant frequency is related to the thickness of the composite structure, the velocity of propagation, density, stiffness and other properties of the materials of which the layers and substrate composed, and the mode of vibration. However, the order of magnitude of the resonant frequency for a given thickness is substantially the same for the various materials which may be used or which have been mentioned by way of example. The resonant frequency for the same body in thickness shear mode of vibration is different from that in thickness of extensional mode of vibration, but still of the same order of magnitude, the ratio being approximately 2.
In the case of Cadmium Sulfide layers a layer thickness from about 0.2 to 0.6 microns corresponds to a half-wave length for a resonant frequency of 5 GHz., with greater thickness corresponding to proportionately lower resonant frequencies. Thus for 30 MHz. (20 million cycles per second) resonant frequency a corresponding layer thickness is from 33 to I microns.
There is a certain range of frequencies within which our resonator may most advantageously be used. One of the factors determining the upper frequency at which the resonator may most advantageously be used is the range of thicknesses available in the substrate. Roughly the effective coupling factor of the device decreases with the square root of the ratio of acoustic half-wave lengths in the substrate to film thickness.
Other factors which have a bearing on the highest frequencies at which the device is advantageously used are the Q of the substrate, the possibility of using the substrate with a negative temperature coefficient to compensate positive temperature coefficient of the layer, and dimensional tolerances. One of the advantages of using quartz as a substrate is its high Q, but this value falls off at higher frequencies. For example at 500 MHz. the quartz substrate in a piezoelectric resonator has a higher 0 than a cavity resonator whereas at 5,000 MHz. GHz.) the Q is lower than in the resonant cavity, which becomes relatively smaller in physical dimensions at higher frequencies, so that dimensional tolerances of a cavity resonator are less ofa problem at 5 to GHz. than at 500 MHz.
Another advantage of using quartz substrates is that quartz may be so cut as to provide a negative temperature coefficient, whereas other practical substrate materials which might be considered to provide a low Q at a higher frequencies do not exhibit a negative temperature coefficient of frequency.
Dimensional tolerance control to obtain the desired resonant frequency also becomes more difficult in applying the thinner layers required for high frequencies especially above IOGHz.
There is also a lower value for the frequencies at which our device is most advantageously used. It is difficult to apply a high quality piezoelectric layer at good adherence to a substrate above a thickness of about microns, which corresponds approximately to a resonant frequency of the order of 30 MHz. Although other good resonant structures are available at the lower frequencies none of these are transformers.
Our device operates most advantageously, therefore, in the range of film thicknesses of the order of 0.2 to 100 microns, which for most materials result in a frequency range from 30 to 50 MHz. to 3 to 10 GHz.
As shown in FIGS. 1 and 2, the layers 14 and 16 are shown smaller in diameter than the substrate 12 although this is not necessary. The electrodes 18, 20, and 22 in turn are smaller in diameter than the piezoelectric layers 14 and 16. This is preferable, although the maximum radial dimensions may be the same if portions are cut back from the circumference where leads are taken off.
In the embodiments of FIGS. 1 and 2, for example, the substrate may be 1 centimeter in diameter and 100 microns thick. The metal layers or electrodes may be from 2 to 10 millimeters in diameter and the cadmium sulfide layers may be 5 millimeters to l centimeter in diameter. Thus, in the embodiment illustrated the electrode diameter is of the order of 40 percent of the diameter of the cadmium sulfide layers, and the diameter of the cadmium sulfide layers is of the order of 50 percent to 100 percent of the substrate diameter. The electrode thickness is of the order of 1 percent to 30 percent of the piezoelectric layer thickness, which is of the order of l percent to 10 percent of the substrate thickness.
The arrangements illustrated are capable of operation at ultrahigh frequencies, useful, e.g., in UI-IF television circuits. They have substantially higher Q than can be realized with conventional coupled coil air core transformers and can be made much smaller. They provide improved frequency selectivity, acting both as transformers and filters. They permit direct-current isolation of the input from the output. The devices can be made very small and they are compatible with other thin film technology and can be used with integrated circuits. As filters they introduce less insertion loss, have better temperature stability and greater resistance to shock and vibration than inductance-capacity-type filters heretofore available in the high frequency range.
The thin film transformers and filters described have a number of advantages over what has been done before. As transformers, these devices have the following advantages over air core transformers:
l. more miniature 2. more frequency selective 3. able ,to operate at higher frequencies.
As filters, these devices have the following advantages over LC (inductor-capacitor) filter networks:
1. more miniature 2. more frequency selective 3. less insertion loss 4. better temperature stability 5. higher resistance to shock and vibration.
As filters, these devices have the following advantages over cavity type filters:
l. more miniature 2. more frequency selective.
As filters these devices have the following advantages over filters sold under the trademark Uniwafers consisting of a collection of acoustically isolated resonators on a single wafer of quartz:
I. able to operate at higher frequencies 2. do not require external transformers and capacitors.
As filters these devices have the following advantages over crystal quartz resonators connected in a filter network:
I. more miniature 2. able to operate at higher frequencies 3. do not require inductors to obtain a broad band pass.
In general, the devices are compatible with thin film evaporation techniques (these techniques are used in the fabrication of integrated circuits). As filters the devices may find a large volume use in UHF television circuits since the UHF band is from 470 to 890 MHz.
When preparing frequency selective devices with multiple films having alternate layers with c axes differently oriented, it will be understood that in the evaporation process suitable techniques are employed for reversing or changing the c axes after each layer of desired thickness has been built-up. For example, when producing units of the type illustrated in FIG. 6 when the cadmium sulfide vapor is deposited with an angle between the molecular beam and the plane of the substrate to obtain a shear response, the substrate is either tilted back and forth from one position to the other after each layer of desired thickness has been deposited to reverse the tilt of the c axis or the substrate is rotated 180 around an axis perpendicular to its surface, or some other means is used to produce reversed tilt of the c axis. For example, there may be means to move the source from one side to the other side.
In the aforesaid copending patent application of Curran and Berlincourt a composite resonator is illustrated in which it is not necessary for the driving element consisting typically of a cadmium sulfide film to be precisely one-half wave length in thickness. The input frequency is such that there is an integral number of half-wave lengths in the composite structure. However, in the embodiments of our invention which employ a plurality of layers of material on the same side of a substrate as in FIGS. 1 to 6 we prefer to maintain the relationship between the input frequency and the thickness of the piezoelectric layers such that the layers are very closely one-half wave length in thickness in order to avoid partial cancellation of energy and in order to maintain the maximum possible effective coupling. Nonetheless, our invention is not limited to such arrangements and our devices may be arranged to overcome the partial cancellation of output.
FIGS. 7 and 8 illustrate that as a result of the stress distribution in the composite structure the films should be distributed on each side of the substrate if the piezoelectric layer is not exactly one-half wave length thick at the principal resonant frequency of the composite structure. FIGS. 7 and 8 illustrate in fragmentary from structures in which the thickness of the composite structure is such as to provide seven half-wave lengths of variation in stress. The curve 126 represents the stress distribution with respect to an arbitrarily chosen axis 128 in a case where the thickness of the cadmium sulfide piezoelectric layer is less than one-half wave length at the design frequency of the composite structure.
It will be observed that in layer 14, complete cancellation of the stress takes place. With more than two piezoelectric layers cancellation effects resulting from deviation from one-half wave length would be severe even with layer thicknesses deviating little from precisely one-half wave length. Cancellation effects may be minimized by applying layers to both sides of the substrate. Although not limited thereto, best results are obtained by dividing the layers, one-half on each side of the substrate. In the diagram of FIG. 8 there are two layers on substrate 12 with the layers 14.and 16 on opposite parallel surfaces of the substrate 12. The arrangement shown is symmetrical and cancellation effects do not take place even though there is the same deviation in thickness of the layers 14 and 16 from one-half wave length as shown in FIG. 7.
A schematic and circuit diagram of a four-terminal device employing the balancing principle of FIG. 8 is shown in FIG. 9 but in this case piezoelectric layers 134 and 136 with c axes and 31 in opposite directions are deposited upon the substrate 12. Electrodes 138 and 140 on the upper and lower surfaces of the substrate 12 are connected to terminals 142 and 144 respectively. On the lower surface of the piezoelectric layer 136 is an electrode 148 shown as grounded in this embodiment. Correspondingly, on the upper surface of the piezoelectric layer 134 is an electrode 150 connected to terminal 152. The arrangement of FIG. 9 forms a four-terminal device, with terminals 142 and 152 constituting the other pair. A three-terminal device is formed if terminals 142 and 144 are connected together by a conductor 146 and terminal 148 is connected to ground. In this manner a step-up voltage ratio of l to 2 may be achieved, if desired, utilizing the terminal 144 as an input terminal, and terminal 152 as an output terminal.
Where higher ratios of transformation are desired, additional layers of piezoelectric material may be deposited on each of the surfaces of the substrate 12 such as the multiplelayer arrangement of FIG. 5. However, where higher ratios of transformation are needed, we prefer in employ a cascading arrangement of successive 2 to l transformers as illustrated in FIG. 10 if it is desired to retain the maximum possible value of the Q. In the arrangement of FIG. 10, three units 154, 156, and 158, each corresponding to a 2 to 1 ratio unit such as generally illustrated in FIG. 2 or FIG. 3 are cascaded so as to obtain a ratio of 8 to l. Impedance matching is necessary.
The terminals are rearranged so that each unit 154, 156, and 158 constitutes a 2 to l step-up transformer. The input terminals 26 and 28 are connected across one of the layers 31, and the output terminal 24 applies the doubled voltage from layers 30 and 31 of unit 154 in series to an input terminal 26' of unit 156. Four times the input voltage appears at the output terminal 24 of unit 156. This voltage is applied to the input terminal 26" of unit 158 so that 8 times the original voltage appears at the output terminal 24" of unit 158. It will be understood that FIG. 10 is merely diagrammatic and that the units may or may not be mounted upon a common substrate with a physical arrangement upon the substrate such as illustrated in FIG. 4 of this application of somewhat like that of FIG. 8 of the copending application of Curran and Berlincourt.
In the arrangement of FIG. 11 the need for reversing the polarization of successive layers of piezoelectric material in a multilayer structure is obviated by connecting alternate layers in parallel.
The substrate 12 carries on its upper surface successive layers 162, 164, 166, and 168, all with their piezoelectric axes in the same direction, namely away from the substrate 12. The substrate 12 likewise carries on its lower surface layers of piezoelectric material 170, 172, 174, and 176 also having all of their piezoelectric axes in the same direction, namely away from the substrate 12. Electrodes are applied to each surface of each piezoelectric layer. The input terminal 152 is connected to the top surfaces of the piezoelectric layers 162 and 166 through leads 188 and 186. Return terminal 202 is connected to the top surfaces of layers 168 and 164 and the bottom surface of layer 162 through leads 190, 192, and 194. Thus, the electric field in layers 162 and 166 are 180 out of phase with respect to the electric fields in layers 164 and 168. As a result, at the principal resonance of the composite structure the acoustic waves generated in layers 162, 164, and 166, and 168 add constructively.
The output terminal 200 is connected to the bottom surfaces of the piezoelectric layers 170 and 174 through leads 196 and 198. Return terminal 147 is connected to the top surface of layers and the bottom surfaces of layers 172 and 176 through leads 180, 182, and 184. As a result, at the principal resonance of the composite structure the voltages generated across layers 170, 172, 174, and 176 are constructively combined to produce a maximum signal at output terminal 200.
Resonators have been described in which the composite structure of substrate and layers vibrates at a multiple of the fundamental frequency of the composite structure, and the thickness of a deposited layer is a half-wave length for the harmonic at which vibration takes place, or is relatively close to a half-wave length. However, the invention is not limited thereto. That operation may effectively take place at lower harmonics of the fundamental frequency of the composite structure may be better understood by considerations of cases represented by FIGS. 12 and 13.
These are cross-sectional views with electrodes and connections now shown to avoid unnecessary complication. Both elements are identical, the only difference being that the element of FIG. 12 is driven at f (the fourth harmonic of the fundamental frequency of the composite structure) and the element of FIG. 13 is driven at f which is 2 j}. The space variation of stress is shown schematically in both cases. Each layer in FIG. 12 is M4, each layer in FIG. 13 is M2; yet the effective electromechanical coupling is the same in each case. It is true that in general a higher frequency is preferred as advantage is taken of the capability of high frequency operation afforded by the use of deposited films to obtain thin layers.
If the film thickness becomes greater than M2 cancellation effects occur and the coupling factor k decreases. For film thicknesses less than M2 It depends on the ratio of active to inactive thicknesses with allowance for the sinusoidal variation of stress. Thus in the illustrations represented by FIGS. 12 and 13 with the driving layer M2 at the eighth harmonic, the device will work well at harmonics: 8, 7,6, 5,,and 4. These harmonics would represent layers having thickness which are integral fractions of wave lengths, respectively one-half, seven-sixteenths, three-eights, five-sixteenths, and onequarter. Coupling will be the same at the eighth and fourth harmonics and slightly higher between. A fairly good quantitive comparison of the coupling factors at the various harmonics is the (average stress)/(peak stress) ratio in the driven area for the condition of a constant ratio of driven to undriven thickness. For the construction represented by FIGS. 12 and 13 this is as follows:
Average stress Harmonic number: peak stress the output layer is the layer 206 adjacent the substrate 12. The stress distribution curve 208 in FIG. 12 represents the fourth harmonic of the fundamental frequency for the composite In FIGS. 12 and 13 the input layer is the outer film 204 and 1 structure and the stress distribution curve 210 in FIG. 13
represents the eighth harmonic of the fundamental.
An advantageous arrangement for stepped up voltage as well as filter action is illustrated in FIG. 14. An output layer 212 is mounted upon one surface of the substrate 12 and the four input layers 214, 216, 218, and 220 are mounted upon the opposite surfaces of the substrate 12. The total thickness of the input layers corresponds to the thickness of the output layer, for example, the thickness of the output layer may be M2 at the eighth harmonic of the fundamental frequency of the composite structure whereas the four input layers, 214, 216, 218, and 220 add up to M2 at the eighth harmonic.
In this case the input section consisting of the layers 214, 216, 218, and 200 is composed of four layers connected in parallel and with polar axis in alternate directions as indicated by the alternating c axes 222. Such a parallel arrangement is especially convenient when employing shear mode layers with alternate layers having their c axis tilting in different directions as in FIG. 15.
The connection of FIG. 14 as shown or modified to employ film .with shear mode of vibration, leads to a step-up of ratio 4. Reversed input and output connections change the step-up to one-quarter. One of the advantages of this arrangement is that the four-layer section degrades the Q of the substrate (and the overall coupling if the multilayer section is the output section) far less than if the layer were the same thickness as the layer on the opposite surface.
If the upper film 212 is M2 in thickness, each lower film layer is M8 thickness. On the other hand if the upper layer 212 is M4 in thickness, the lower layers 214, 216, 218, and 220 are each M16.
Referring to the foregoing table of Average Stress/Peak Stress for various overtones, when the arrangement of FIG. 14 is operated at the ninth or tenth harmonic, layer 214 in the four layer group toward the inside would contain reversed stress and might therefore be left unconnected. As shown the best results are obtained by operating at one of the overtones of the group consisting of the harmonics 4, 5, 6, 7, and 8. For higher harmonics it is preferable to make the film thicknesses a smaller portion of the overall thickness.
Under optimum conditions the last outside film of the multilayer section, namely the film 220 may be a high Q metal film in order to raise the coupling factor slightly, since this is where the stress is lowest. Since the average stress in each layer varies with position, under ideal conditions the layers need not be made equal in thickness, with the more highly stressed layers away from the outside made thinner so that the voltages generated in each layer are substantially equal and can be connected in parallel with minimum loss.
While there have been described what at present are believed to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is aimed, therefore, to cover in the appended claims all such changes and modifications as fall within the true spirit and scope of the invention.
It is claimed and desired to secure by Letters Patent of the United States:
1. A high frequency piezoelectric resonator device for operation at a frequency in the range represented by a wavelength of the order of from 0.2 to microns, said device comprising in combination a wafer substrate, a plurality of alternate superposed layers of piezoelectric material of first and second different types with respect to piezoelectric axes and capable of acoustic vibrations, and a plurality of electrodes, there being at least two of said layers of the first type having parallel faces and having piezoelectric properties, each electrode being applied to a different one of said faces, the superposed layers being mounted on said substrate with parallel faces in force transmitting relation to each other with means for energizing one of the piezoelectric layers, the layers and substrate together forming a composite structure having an overall thickness defining a resonant frequency in a thickness mode of vibration corresponding to 1 In times the frequency at which the resonator is to be operated, where n is any integer, and the thickness of each layer is substantially in the range of from 0.2 to I00 microns and is of the order of 1 percent to 10 percent of substrate thickness.
2. A high frequency piezoelectric resonator device for operation at a frequency in the range represented by a wavelength of the order of 0.2 to I00 microns, said device comprising in combination a wafer substrate, a plurality of superposed layers of piezoelectric material mounted thereon with parallel surfaces in force transmitting relation to each other with means for energizing one of the layers, together forming a composite structure having an overall thickness defining a resonant frequency in a thickness mode of vibration corresponding to l/n times the frequency at which the resonator is to be operated, where n is any integer, and the layer thickness is substantially in the range from 0.2 to 100 microns and is of the order of l percent to l0 percent of substrate thickness, the piezoelectric axes of successive layers being tilted from a normal to the surface.
3. A device as in claim 2 wherein the piezoelectric axes of successive layers are tilted in different directions from the norma].
4. A high frequency piezoelectric resonator device comprising in combination a wafer substrate, a plurality of superposed layers of piezoelectric material mounted thereon with parallel faces in force transmitting relation to each other with means for energizing one of the layers, together forming a composite structure having an overall thickness defining a resonant frequency in a thickness mode of vibration corresponding to l /n times the frequency at which the resonator is to be operated, wherein n is any integer and the layer thickness is substantially in the range from 0.2 to 100 microns and is of the order of 1 percent to 10 percent of substrate thickness there being alternate layers of piezoelectric material capable of acoustic vibrations, said alternate layers being of different types with respect to'their piezoelectric axes, said layers of the first type having parallel faces and having piezoelectric properties with piezoelectric axes extending in a predetermined direction, the layers of the second type having its piezoelectric axes oriented in a different direction the axes of both types being titled with respect to a normal from the parallel faces, and said layers of the first type having a plurality ofelectrodes, each electrode being applied to a different one of said faces, each of at least three of such electrodes being adapted for connection to an exterior terminal.
5. A device as in claim 4 wherein the layers of the first and second types differ with respect to piezoelectric response.
6. A device as in claim 4 wherein the layers of the second type have opposite faces which are electrically connected.
7. A device as in claim 4 wherein the layers of the second type are inactive piezoelectrically.
8. A device as in claim 4 wherein the layers of the first and second types are piezoelectric with piezoelectric responses differently oriented.
9. A device as in claim 4 wherein the layers have a thickness shear mode of vibration with piezoelectric axes of layers of the first type tilting at one angle with respect to a normal to the layer face and piezoelectric axes of layers of the second type tilting at a different angle with respect to a normal to the faces of the layers.
Patent Citations
Non-Patent Citations
Referenced by
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Projected ranking and expected results
Some notes and comments about the Independents:
1) Notre Dame is projected to be pretty decent, right around as good as last year, which makes sense, given varying positive and negative indicators (turnover margin likely to improve, return a good amount of proudction, but have been slipping in recruiting, had material draft losses, and 2011 was already a bit of a positive outlier). Unfortunately for them, the schedule looks like a nightmare, which means they're likely to hover around .500, maybe a bit better.
2) BYU is likely to improve quite a bit from last season's struggles. They're picking up recruiting, they return a lot of production, and they didn't lose anyone talented enough that the NFL wanted to draft them.
3) Army-Navy looks a bit more interesting than usual. Navy still looks like the better team, but it's pretty close.
The next two tables show key statistics and details underlying the projections, from prior history and performance to luck-related statistics to key indicators of incoming and outgoing talent. Below is a brief explanation of some of these items:
Rank - Projected 2012 ranking, from 1 to 124
2011 Rank - 2011 ranking using the current compu-picks model, from 1 to 120 (does NOT include the four 1-A newcomers)
Prev 4 yr - ranking of the average rating from 2007-2010, from 1 to 120 (does NOT include the four 1-A newcomers)
Injuries - starts lost to injury during the 2011 season, from Phil Steele
Fumble Luck - the number of net turnovers in 2011 due to fumble luck
Recruit Rank - ranking of past 4 years of recruiting (each year equally weighted), from scout.com
Recruit Trend - the difference between the past 3 years of recruiting and the previous 4, ranked from best to worst
Starters - returning offensive / defensive / special teams (kicker and punter) starters, per Phil Steele magazine (* if the QB returns), with some edits due to subsequent news
Returning Yards, Tackles, Int, Sacks, Lettermen - returning production and roster depth; lettermen taken from philsteele.com, with the other stats calculated from cfbstats.com.
Draft Losses - based on the 2012 draft
Key Statistics - Performance, Luck and Coaching
Talent Inflows and Outflows
The next table shows probability distributions for the projections, based on 5,001 season simulation runs. Please note that a . indicates zero odds, while 0% indicates a non-zero probability that just rounds to 0%. The first table breaks down results across all games, while the second breaks down results across league games only.
Projected Results - All Games
There are a few important notes and caveats I need to make about this model:
1) Compu-Picks does not endorse implicitly or explicitly any form of illegal gambling.
Compu-Picks is intended to be used for entertainment purposes only.
2) No guarantee or warranty is offered or implied by Compu-Picks for any information provided and/or predictions made.
3) This preseason model is primarily based on the main compu-picks model. Essentially, it attempts to predict how well a team will rate given its rating history, as well as a number of other data points, such as returning starters, draft talent lost, turnovers, recruiting, etc. This means, among other things, that the rankings are power rankings based on how good a team projects to be, as opposed to a more cynical (though accurate) model that attempts to project how the BCS will rank a team by making adjustments to favor those with easy schedules and punish those with tough schedules.
4) I have provided adjusted division (or league) odds in a couple of instances. For the Big Ten Leaders, it shows the odds of each team winning adjusting for the fact that Ohio St and Penn St will both be ineligible. The same is true for the ACC Coastal and North Carolina.
5) There is a substantial amount of noise in these projections, which is to be expected given the large number of unknowns (who will have good and bad luck with injuries, which young players will improve and which won't, how specific matchups will come into play, etc.). Right now the standard error is a bit over 0.2 on a scale of about -1 to +1. It's important to look at the projections with this in mind to get a sense of how material the projected differences are. Given a standard error around 0.2, it is safe to project Alabama to be a much better team than Mississippi St, but it is not safe to project Mississippi St to be any better than Arkansas, much less a lot better.
6) At this point, there are a number of model features that need to be investigated further. Chief among these is the distribution of extreme events. It appears that the model may be overstating the probabilities of extreme events, such as 12-0 or 0-12 records, or major underdogs winning their division/league. This overstatement has been reduced compared to last year's projections, but still likely exists to some degree. Please keep this in mind when looking at the distribution of win probabilities.
7) Since there is much less data available for the four 1-A newcomers, the power rating methodology has been more manual and arbitrary. As a consequence, I am somewhat less confident of the projections for those four teams than I am for the other 120 1-A members. Please keep this in mind when looking at the newcomers' projections.
2012 Compu-Picks Blog
Questions, comments or suggestions? Email me at firstname.lastname@example.com

subset: commoncrawl


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2007 Buick LaCrosseChange Make/Model
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2007 Buick LaCrosse Summary
The 2007 Buick LaCrosse is a 4-door, 5-seat Sedan, available in 3 trims, ranging from the CX to the CXS. Upon introduction, the $22,415 CX is equipped with a standard 3.8L, 6-cylinder, engine that achieves 20-mpg in the city and 30-mpg on the highway. an Automatic transmission is standard. The $27,040 CXS is equipped with a standard 3.6L, 6-cylinder, engine that achieves 19-mpg in the city and 27-mpg on the highway. an Automatic transmission is standard.
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Largest Capacity
6.3 cu. ft. Capacity Electric Single Oven Range with True Convection and EasyClean™
LRE3083STCOLOR : Smooth Black Smooth White Stainless Steel
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$999.99Suggested Price
Rated 4.8 out of 5 by 186 reviewers.
Rated 2 out of 5 by Blackrose30 Bad Touch Pad I have had this stove less then two years and have had to have the touch pad replaced once already and now it is out again three months after repair was done. I like this stove but not the fact that this is the second time this has went out and now there is no way to get it fixed unless I buy a new touch pad. This should not go out like this and now no more warenty on it and even if i fix it again how do I know it will not go out again? Like I said, love the stove but I really cannot keep putting money into it like this. June 20, 2015
Rated 5 out of 5 by SandyMac I really love my new electric stove We just purchased all new appliances for our kitchen. Several years ago after a lightening strike we began having problems with our cooktop and oven. I didn't realize how bad the stove and oven were until we began using our new stove and oven. They are easy to use. The oven is a bright blue and I really like not having an element in the bottom. Controls are easy to understand but I have not yet used the convection feature on the oven. I LOVE this new LG appliance. June 18, 2015
Rated 4 out of 5 by emchvz Beautiful addition to our kitchen I have to say this is a beautiful oven! The bright blue interior, the smooth ceramic cooktop, and the large window - it all looks great. I have to say that I was a little disappointed in the touchpad, since our salesperson told us it was going to be glass to match the microwave, but other than that, I'm very happy with the appliance. I also had some trouble figuring out the convection feature. I've never used it before, and when I baked a chicken, it took longer than the manual said, but it did come out very moist and evenly browned. June 15, 2015
Rated 5 out of 5 by Deb I LOVE THIS PRODUCT THIS IS THE BEST STOVE I HAVE EVER PURCHASED, LG IS THE BEST I WILL NEVER BUY ANOTHER BRAND, I ALSO HAVE LG WASHER DRYER AND DISHWASHER NEXT WILL BE MY REFRIGERATOR.... HIGHLY RECOMMEND TO ALL June 13, 2015
Rated 5 out of 5 by lg oven Range My husband and I shopped for ovens for about three to four months. We found this one at a deal so we bought it. I love the smooth surface because it is easy to clean, shines and looks nice. The oven surface is easy to clean and very appealing in color. Plays music once the oven has reached preheat temp. Love the dual burner choice. That gives me three little burners or two large and two small. Our children are grown so we use the smaller one more. The large ones come in handy for family dinners. June 7, 2015
Rated 5 out of 5 by LoriK This product is easy to use and cooks wonderfully. We bought our stove about a month ago and we love it. It is easy to use and bakes great! We love the convection bake and roast! Love the 5 burners too! The warming burner comes in handy. Easy to clean and looks great too. I wasn't sure about the color on the inside of the oven, but it grows on you. I love it now! Would recommend this to everyone! The price was great too, we bought it on sale! June 6, 2015
Rated 4 out of 5 by TRDUNNE Convection??? We are having a hard time figuring out the convection part. According to the directions, when we used the magical formula for cooking in convection mode, the item was raw. Work in progress - could use better or more accurate instructions. June 2, 2015
Rated 5 out of 5 by Glenn Wish I did not wait so long! Needed a new range as a step in my kitchen remodel and forgot how much I enjoy cooking fresh food. May 29, 2015
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Largest Capacity
The Largest electric oven in the industry*, now with EasyClean™ Technology can handle all of your family's cooking needs without worrying about cleaning up the mess in your oven. Whether you're baking large batches of cookies or a roast for the holidays, this oven can fit it all.
*Based on manufacturers' published specifications of freestanding electric single oven ranges, April 2012.
Design, features and specifications subject to change without notice. Screen images simulated and/or dramatized. Some features in videos may not be available on all models. Please refer to the TECHNICAL SPECIFICATIONS tab for a complete list of features by model.
Design, features and specifications subject to change without notice.


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Eve Plumb's THREE FACES OF EVE to Open at Michael Ingbar Gallery, 2/21
Eve Plumb, actress and artist, has been working in television, movies, and stage since the age of six, and has been painting steadily over 20 years. Eve has been expanding her view from still life for her subject matter to include images from film noir movies and New York City. Her exhibition Three Faces of Eve will be on view at Michael Ingbar Gallery, Thursday, February 21 to Saturday, March 16, 2013.
Eve's artworks have had successful showings in galleries across the US. She is a spokesperson for Fredrix Canvas and regularly donates artworks to charity including Wildhorse Ranch Rescue in Arizona, Broadway Cares/Equity Fights Aids, and the Laguna College of Art and Design.
Eve is most remembered for her portrayal of "Jan" on "The Brady Bunch," but she has also been seen in other series and many television movies. Along with her television and film work, Eve studied improv comedy at The Groundlings School in Los Angeles and appeared on stage off-Broadway in Nora Ephron and Delia Ephron's "Love, Loss, and What I Wore," "Miss Abigail's Guide to Dating, Mating & Marriage," and at Lincoln Center with Florence Henderson in "Broadway Backwards 5." She can be seen in the upcoming film "Blue Ruin" and an episode of "Law and Order: Special Victims Unit."
Please join Eve for the opening reception on: Thursday, February 21, from 6:00 pm to 8:00 pm. RSVP for limited seating for a gallery talk by Eve on Thursday, February 28th at 7pm. For more information, visit www.michaelingbargallery.com and www.eveplumb.tv.
Artwork: "Bang, Bang, Bang", Canvas, 40" x 53", Ed. of 25
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The world's most famous monk has received birthday gifts from afar: a cake at Glastonbury, a portrait painted by George W. Bush in Texas and a road named after him in India. Yet as the Dalai Lama turned 80 yesterday, according to the Western calendar, the Chinese authorities stayed silent about the spiritual leader they condemn as a divisive and dangerous figure. Ordinary Tibetans have defied a ban on celebrating his birthday, which fell on June 21 in the country's calendar. Tibetans have been holding his picture at prayers and picnics in several Tibetan areas of China,
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The Russian Orthodox Church has been heavily criticised in recent months for its perceived tacit support of Vladimir Putin's aggression in Ukraine. The view that the closeness between the Russian Orthodox Church and the Russian state is undermining religious freedom there and in Russia was reiterated during a meeting at Lambeth Palace last week to discuss religion in Ukraine. Some 30 church leaders signed a document to commit to "formal and informal partnerships that will advocate religious freedom and social justice in Ukraine through international networking and the sharing of resources".
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In July 2006, Tiens Group selected eFuture's ONE POS-ERP R2003 Super Market Management System for its Bannerstore Supermarket. Since its selection, the R2003 Super Market Management system has been successfully implemented in Bannerstore's headquarters back-office, six subsidiary stores, 17 direct-sales stores and 23 franchised chain stores.
About Tiens Group Co., Ltd.
Founded in 1995 by Mr. Li Jinyuan, Tiens Group Co., Ltd. (Amex: TBV) is a large-scale global enterprise with operations in over 190 countries and regions and with a customer base of over 16 million worldwide. Since 1995, Tiens Group has maintained continual, stable, and rapid growth. With an anchor business in advanced biotechnology, particularly in the areas of health food, health care, beauty care and home care products, Tiens Group is also involved in financing, real estate development, education, cultural exchanges, and modern logistics. Tiens Group is headquartered at the Henderson Center in Beijing, China, and has production plants in the Wuqing New Technology Development Zone of Tianjin, China.
Tiens Group is a direct selling company that is based on advanced
biotechnology devoted to developing health and wellness products and a
culture for a healthy lifestyle. Tiens Group operates
|SOURCE eFuture Information Technology Inc.
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Area homes flood with water and sewage
In the wake of Wednesday's torrential downpours, basements in Chillum, Md. flooded to the ceilings in some cases, while homes in Northwest D.C. flooded with sewage when tree roots broke pipelines.
Flood waters rage in Rock Creek, create hassles for Virginia drivers
Emergency officials in Maryland say crews have rescued motorists who got stranded in high water on closed roads as heavy rains bring flooding to the mid-Atlantic region.
Massive storm wreaks havoc with tornadoes then flooding across south
People were plucked off rooftops or climbed into their attics to get away from fast-rising waters when nearly 2 feet of rain fell on the Florida Panhandle and Alabama coast in the span of about 24 hours.
Red Top Cab driver narrowly escapes flooded road in Vienna
Flash flood watches and warnings were active for most of the day Wednesday. In Vienna, VA, on Browns Mill Road, NewsChannel 8/ABC 7 reporter Tom Roussey encountered cab driver trying to drive through the flooded road.
Weekend rain causes floods throughout D.C.
Throughout the metro area, the excessive rain of the weekend meant flooded parking lots and playgronds, busy commuter routes shut down, and even one giant sinkhole.
Spring Showers Bring Cherry Blossom FlowersComment
A soggy Saturday and first half of Sunday may dampen weekend plans, but it's good news for the cherry blossoms.
Wintry mix drops significant snow but mostly spares D.C. area
Schools in western and northern Maryland are closing or delaying openings and transportation officials are warning motorists to plan ahead as a snow storm moves through the mid-Atlantic region.
Circulator bus stuck in sinkhole in Southeast D.C.
Police in Washington say a Circulator bus needed a tow after a sinkhole opened up along its route in southeast Washington.
Wallops Island rocket launches postponed by rain
Rainy weather has postponed the launch of three suborbital rockets from NASA's Wallops Island facility on Virginia's Eastern Shore.
South Florida flooding widespread after 18 inches of rain
A massive deluge of rain has left some portions of South Florida underwater after more than a foot of rain fell over a 24 hour period.
Nelson Mandela memorial service: Crowds gather despite rain
Joyous, singing South Africans gathered in the rain Tuesday to honor Nelson Mandela at a massive memorial service that is expected to draw some 100 heads of state and other luminaries.
Christmas tree bumper crop in Virginia
Well-timed rain is likely to create a bumper crop of Christmas trees in Virginia this holiday season.
Hurricane Sandy anniversary marked a year after massive stormComment
A year ago Tuesday marks the one year anniversary of a storm that ravaged the northern Mid-Atlantic coast.
D.C. rainy Monday: Timing and intensityComment
The dry spell and hot weather will soon be over with a strong front sliding through today.
D.C. Weather Turning Dry; Rain NeededComment
Although rain was plentiful this summer, recent dryness is starting to creep up on the D.C. area.
Colorado flooding 2013: Trapped people rescued from Boulder apartment balcony
Firefighters and first responders in Boulder, Colo. were able to come to the rescue for several people who were trapped on their apartment balcony during the brunt of heavy rain and flooding in the area.
D.C. Summer: Soggy and GreenComment
The grass is green and the water table is running much higher than it typically is for late-summer. How wet has it been?
Ocean City tourism dives due to bad weather all summer
Tourism officials say that dreary, often rainy weather has kept visitors away from Ocean City in droves throughout the summer, the Baltimore Sun reports.
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Welcome To The Community
Originally posted by relocator
Awww...Bless your heart. Welcome!
Have A Happy New Year to All!edit on 31-12-2012 by relocator because: (no reason given)
Originally posted by ValentineWiggin
Welcome to ATS! Quite intimidating, isn't it? That is how I felt before I joined. For the most part I would call us a loving yet occasionally dysfunctional family, you will be comfortable in no time! I can't wait to read your stories and contributions to the site
Originally posted by tombangelta
reply to post by DoubleEE
Never put yourself down there are enough people out there who will try and
do that for you.
You present yourself in a clear and concise fashion which trumps most people round here
Including myself


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Valor & Virtue (Issue 4)
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Dr. Dave will present an "Existence of God" seminar in Fort Worth, TX July 10-12.
For more information, call (817) 692-3989.


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More New York Vegetarian Restaurants that offer Delivery and Carryout
Did you know?
You can get results that are 95% more accurate* by entering your location in the box at the top of the screen.
*We confess we made that number up. But we will be able to show you a much more accurate list of restaurants.
Manhattan Vegetarian Restaurants (302)
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Healthy, Indian, Vegetarian, Middle Eastern, Lunch, Dinner
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Delivery $2.50 - $7.50 Depending on distance
Hudson County Vegetarian Restaurants (34)
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Book Search
Goal-Directed Behavior
Series: Frontiers of Social Psychology
This volume presents chapters from internationally renowned scholars in the area of goals and social behavior. The book is organized around a series of topics that are of critical importance to understanding the social-cognitive aspects of goal-directed behavior. In each chapter, the authors offer...
Published October 19th 2011 by Psychology Press
Handbook of Approach and Avoidance Motivation
Of the many conceptual distinctions present in psychology today, the approach-avoidance distinction stands out as one of, if not the, most fundamental and basic. The distinction between approach and avoidance motivation has a venerable history, not only within but beyond scientific psychology, and...
Published May 20th 2008 by Psychology Press