摘要:
The structure of the patent is a substrate wherein a metal electrode, a dielectric thin film, and a further dielectric thin film are adhered onto a piezoelectric substrate. A substrate wherein elastic wave energy is confined in the piezoelectric substrate can be obtained. In particular, when a SiO2 thin film and an AlN thin film are used as thin films 4 and 5, respectively, a substrate excellent in an electromechanical coupling coefficient (k2) and a temperature characteristic of frequency can be yielded by making the film thicknesses of electrodes 2 and 3 and those of the thin films 4 and 5 into optimal values.
摘要:
In a spread spectrum communication using a long spreading code, a spread spectrum signal processing apparatus is provided, which is suitable for performing communication by using a correlator having a size mountable on a portable equipment. The spread spectrum signal processing apparatus has a correlator for correlating between a spread spectrum signal and a given reference signal, an A/D converter for converting a correlation signal into a digital signal, a memory for storing the digital signal from the AD converter as digital data, a signal processor for summing digital data corresponding to each of divided codes C1–C16 and for outputting a result of summation, and a control unit for controlling to apply each of the divided codes C1–C16 in this order repeatedly as a reference signal to the correlator. The signal processor begins a summing process by making reference to a timing signal from the control unit.
摘要:
A surface acoustic wave filter device includes a substrate which includes quartz or the like piezoelectric material having a small temperature coefficient. The substrate has a surface which is formed with interdigital-type unidirectional transducers on input and output sides, each having a positive electrode and a negative electrode. The positive electrodes and the negative electrodes of each of the input side and output side transducers have electrode fingers which are arranged so as to transduce a harmonic wave of a selected order which is higher relative to a fundamental surface acoustic wave.
摘要:
An electronic imaging apparatus includes a connecting section connected to an optical apparatus; an optical element having a preset transmittance with respect to light in a preset wavelength region, incident from the optical apparatus; and an electronic image sensor receiving the light transmitted through the optical element.
摘要:
In order to provide a transducer suitable for an anisotropic substrate having the NSPUDT property, on the anisotropic piezoelectric substrate being cut to have the NSPUDT property, there is formed a transducer structure having an exciting electrode structure (21) and a reflector structure (22). When &lgr; is a wavelength of a fundamental surface acoustic wave, said exciting electrode structure (21) includes a positive electrode (23) having a plurality of electrode fingers arranged at a pitch &lgr; and a negative electrode (24) having at least one electrode finger interdigitally arranged between said electrode fingers of the positive electrode with a center distance of &lgr;/2. The reflector transducer (22) includes a plurality of electrode fingers arranged with a center distance of &lgr;/2, and a distance Lg between said exciting electrode structure (21) and the reflector structure (22) is set to Lg=(2n+1)&lgr;/4 (n being a positive integer).
摘要:
A surface acoustic wave functional element is provided that includes a piezoelectric substrate or a multilayer piezoelectric substrate having a large electromechanical coupling coefficient. Semiconductor layers are formed on the piezoelectric substrate. The semiconductor layers include an active layer and a buffer layer. The buffer layer is formed of a structure that has a lattice constant that is the same as or similar to that of the active layer. In addition, input and output electrodes are formed on both sides of the semiconductor layers. The surface acoustic wave functional element attains a large amplification gain at low voltage, and can be used as part of a transmitting/receiving circuit in a high frequency portion of a mobile communication device.
摘要:
An interdigital transducer used in an elastic surface wave device and including a pair of electrodes each having a common electrode and a plurality of electrode fingers connected to the common electrode, the overlap lengths of electrode fingers being uniform throughout the transducer. Floating electrodes, each having two parallel conductors connected together at one end, are disposed between the interdigital electrode fingers of the paired electrodes to weight the excitation electric field strength.This invention relates to an elastic surface wave transducer.BACKGROUND OF THE INVENTIONAn elastic surface wave device (also referred to as an acoustic surface wave device) used in the VHF band and UHF band as a filter or delay line already known to those skilled in the art. An elastic surface wave device has transmitting and receiving interdigital transducers disposed on a piezoelectric substrate. These transducers are used to convert electrical signals into elastic surface waves or vice versa.A known transducer used in an elastic surface wave device is of the uniform overlap length interdigital type comprising first and second electrodes disposed on a substrate of piezoelectric material, each of the first and second electrodes having a common electrode connected to an external terminal and a plurality of electrode fingers connected to the common electrode, the overlap lengths of the electrode fingers of the first and second electrodes being uniform throughout the transducer.However, the above-mentioned prior art uniform overlap length interdigital transducer has unsatisfactory frequency characteristics. Further, such transducer has a passband width bearing a substantially inverse proportion to the number of electrode fingers.In Proc. IEEE, Vol. 59, No. 3, p.393, March (1971) is set forth a weighting transducer with a so-called "apodized electrode" arrangement for improving the frequency response of the transducer. With this apodized type weighting transducer, the overlap lengths of the electrode fingers are made to vary in proportion to a weighting function, causing the widths of excited elastic surface wave beams to be weighted in proportion to the weighting function. Though a weighting function with respect to the frequency transmitting property of an ideal filter is sin x/x, a practically used function is, for example ##EQU1## APPROXIMATING THE FUNCTION SIN X /X.When the apodized transducers are used as input and output transducers, it is impossible to obtain the product property of the transfer functions of both transducers. For a prominent guaranteed attenuation in the stop band, however, the product property should be attained. Following is the reason why apodised type weighting transducers used as input and output transducers can not provide a desired product of transfer functions. The electrode fingers of the output transducer overlapping each other over a small length can not fully pick up an elastic surface wave having a larger beam width from the input transducer, failing to produce an output signal proportional to the weight of the beam width.To obtain, therefore, the product of transfer functions, an apodized type weighting transducer is combined with a uniform overlap length type transducer. In this case, the electrodes of the apodized type weighting transducer should be made more precisely than in the case with two weighting transducers in order to attain a prominent guaranteed attenuation in the stop band. However, this is difficult to realize.It is accordingly an object of this invention to provide a weighting transducer, which, combined with any other type of transducer, can easily realize the product property of the transfer functions of both transducers.Another object of the invention is to provide a uniform overlap length interdigital transducer with an improved frequency response.SUMMARY OF THE INVENTIONA uniform overlap length type interdigital weighting transducer of this invention is characterized in that a plurality of floating electrodes each having a pair of parallel conductors connected together at one end are disposed on a piezoelectric substrate between the adjacent interdigital electrode fingers of the first and second electrodes. The parallel conductors preferably extend along the entire overlap length of the interdigital electrode fingers of the first and second electrodes. A plurality of the above-mentioned floating electrodes arranged between pairs of interdigital electrode fingers in numbers progressively increasing from the center of the transducer to both ends thereof along the propagation axis of the elastic surface wave can weight the strength of an excitation electric field in proportion to a weighting function.When combined with any other type of transducer, the weighting transducer of this invention which has the electrode fingers overlapped by each other in the uniform length throughout the transducer, can easily realize the product property of the transfer functions of both transducers.Further, the rejection of the side lobe of the weighting transducer of this invention can be easily improved to a larger extent than 10 dB as compared with the ordinary uniform overlap length type transducer.
摘要:
An electronic imaging apparatus includes a connecting section connected to an optical apparatus; an optical element having a preset transmittance with respect to light in a preset wavelength region, incident from the optical apparatus; and an electronic image sensor receiving the light transmitted through the optical element.
摘要:
An electronic imaging apparatus includes a connecting section connected to an optical apparatus; an optical element having a preset transmittance with respect to light in a preset wavelength region, incident from the optical apparatus; and an electronic image sensor receiving the light transmitted through the optical element.
摘要:
A unidirectional surface acoustic wave (SAW) transducer has a substrate which is piezoelectric or electrostrictive, a first IDT (interdigital transducer) electrode disposed on a surface of the substrate and having a plurality of first electrode fingers, and a second IDT electrode disposed on the surface of the substrate and having a plurality of second electrode fingers alternating with the first electrode fingers, and structural elements disposed on the surface of the substrate and arranged periodically in a propagating direction of surface acoustic waves. The structural elements comprise grooves or dielectric films each having a width of λ0/4 or λ0/2, for example, where λ0 represents a wavelength corresponding to a fundamental operating frequency of the unidirectional surface acoustic wave transducer.
摘要翻译:单向表面声波(SAW)传感器具有压电或电致伸缩的基板,设置在基板的表面上并具有多个第一电极指的第一IDT(叉指换能器)电极和设置在该基板上的第二IDT电极 并且具有与第一电极指交替的多个第二电极指,以及设置在基板的表面上并且以表面声波的传播方向周期性地布置的结构元件。 这些结构元件包括各自具有λ/ O / 4或λ/ 2/2的宽度的凹槽或电介质膜,例如其中λ< 表示对应于单向表面声波换能器的基本工作频率的波长。