Abstract: In a configuration in which side beams scan in positions that are offset with respect to a main beam by approximately (¼+n)P or (¾+n)P in the radial direction of an optical disk, a differential signal is generated from push-pull signals of the return lights of the side beams to generate a track-cross signal. In a configuration in which side beams scan in positions that are offset with respect to a main beam by approximately (¼+n)P or (¾+n)P in the radial direction of an optical disk, far-side or near-side light detection results of the return lights of the side beams are processed and computed with respect to a push-pull signal of the return light of the main beam.

Abstract: Disclosed herein are a disc recording medium, a recording apparatus and a playback apparatus, more concretely, the present invention provides a disc recording medium wherein a circular track is created in advance to be used for recording data as a groove or a land, said track is wobbled to contain approximately fixed number of wobbling periods as counted in a longitudinal direction of said track, and said track includes rotational-angle marks each showing a predetermined rotational angular position on said disc recording medium. As a result, the precision and the reliability of recording can be attained.

Abstract: A detecting-element assembly (40) is configured such that a piezoelectric element (51) is housed in a casing body portion (43) of a casing (42), and is attached to a housing portion (22) of a flow path formation member (20) via a flange portion (41). Therefore, the path between the piezoelectric element (51) and the position of attachment of the detecting-element assembly (40) is elongated, whereby ultrasonic waves which leak into the interior of the detecting-element assembly (40) from the piezoelectric element (51) become unlikely to reflectively return from a joint. Thus, the influence of, for example, noise stemming from reflected waves is reduced, thereby enhancing the accuracy of detection. An average clearance of 1 millimeter or more is provided along the outer circumferential surface of the casing body portion (43) of the detecting-element assembly (40), whereby a problem of collected foreign matter is unlikely to occur.

Abstract: A gas sensor includes an element case 42 with an internal peripheral surface formed as a taper surface 100. A portion of a housing section 43 surrounded by the taper surface 100 and a protective film 48 is filled with a filler 49. When the filler 49 thermally expands at high temperature, the filler 49 is subjected to a component of force in an upward direction by the taper surface 100. Therefore, projection of an element portion 44 involving deformation of the protective film 48 is suppressed, a change &Dgr;L of a propagation distance L to a reflecting section 33 is also suppressed, and a detection accuracy never decreases. In addition, reverberation is reduced.

Abstract: A gas concentration sensor includes a measurement chamber for measuring a concentration of a specific gas component in a gas under measurement; an inflow path for allowing inflow of the gas under measurement thereinto and an outflow path for allowing outflow of the gas under measurement therefrom; a reflection wall for reflecting an acoustic wave; and an acoustic wave transmitting-receiving element having a transmitting-receiving surface adapted to transmit an acoustic wave toward the reflection wall and receive an acoustic wave reflected from the reflection wall. The concentration of the specific gas in the gas under measurement is detected on the basis of a propagation time between transmission of the acoustic wave and reception of the reflected acoustic wave. When a predetermined member having the sensor attached thereto is placed in a horizontal plane, the transmitting-receiving surface faces downward. A recess is formed in a peripheral portion of the reflection wall.

Abstract: A gas sensor (10) including a measurement chamber (28) into which a gas GS is flown and a detection element main body (40) facing the measurement chamber (28). The detection element main body (40) includes an element case 42, and a protective film (48) is adhered to a bottom surface thereof. An acoustic matching plate (50) and a piezoelectric element (51) of a substantially columnar shape and a tube body (52) provided in a position surrounding the acoustic matching plate 50 and the piezoelectric element 51 are housed in the element case (42). A filler is then introduced into the element case (42), whereby the acoustic matching plate (50), the piezoelectric element (51), and the tube body (52) are sealed by a filled layer (99).

Abstract: An ultrasonic-wave propagation time measuring method which enables determination of accurate propagation time, a gas-pressure measuring method, a gas-flow-rate measuring method, and a gas sensor. A reception wave which has been transmitted and received by an ultrasonic element 5 is shaped and integrated by an integration circuit 67 to obtain an integral value. A peak value of the integral value is held by a peak-hold circuit 39. As to detection of gas concentration, a resistance-voltage-division circuit 41 sets a reference value on the basis of the peak value, and a point in time when the integral value of the reception wave is judged by a comparator 43 to have reached the reference value is regarded as an arrival time. Subsequently, a gas concentration is detected on the basis of a period between the emission time and the arrival time.

Abstract: The present invention provides a method and apparatus using a gas concentration sensor for accurately controlling an air fuel ratio in an internal combustion engine, featuring in that before the fuel-vaporized gas purged from the canister enters into the intake manifold whereat the sensor detects the gas concentration of the purged gas, the sensor is adjusted so as to adjust a zero point (or zero output level) of the sensor output. In step 100 of FIG. 7, a judgment is made as to whether the flow rate of air reaches a predetermined level. In step 110, processing for zero-point correction of the gas concentration sensor is performed. Specifically, in a state in which the purge valve 17 is closed, concentration of purge gas is measured by use of the gas concentration sensor 4, and a sensor output S1 at that time is obtained. Subsequently, the sensor output S1 is compared with a correct sensor output S0 in order to obtain a difference &Dgr;S therebetween.

Abstract: An ultrasonic-wave propagation-time measuring method and gas concentration sensor are disclosed in which a reception wave which has been transmitted and received by an ultrasonic element 5 is subjected to full-wave rectification in order to obtain a full-wave-rectified wave, which is then integrated by an integration circuit 37 to obtain an integral value. A peak value of the integral value is held by a peak-hold circuit 39. As to detection of gas concentration, a threshold-level calculation section 21e sets a reference value on the basis of the peak value, and a point in time when the amplitude of a reception wave having undergone full-wave rectification is judged by a comparator 43 to have reached the reference value is regarded as an arrival time. Subsequently, a gas concentration is determined on the basis of a period between the emission time and the arrival time.

Abstract: When a sensor has deteriorated, the propagation time T1′ of a first reflection wave becomes greater than the propagation time T1 of a first reflection wave as measured in a new sensor. If measurement of the concentration of a specific gas is based on the propagation time T1 of the first reflection wave as measured in the new sensor, gas concentration cannot be determined accurately. By contrast, a reflection wave other than the first reflection wave (for example, a second reflection wave) is merely reflected off the surface of the ultrasonic element and is not affected by the internal structure of the ultrasonic element. Therefore, even when the sensor is deteriorated, the propagation time T2, T2′ of the second reflection wave exhibits less variation and is less susceptible to deterioration of the sensor.

Abstract: A gas concentration sensor comprises an ultrasonic element 33 opposite a reflection surface 34. A depression 34a is formed on an edge portion of a reflection surface 34 which is in contact with a side wall of a measurement chamber 32 such that a bottom surface of the depression 34a is substantially in parallel with the reflection surface 34. The distance between the ultrasonic element 33 and the edge portion of the reflection surface 34 becomes greater than the distance between the ultrasonic element 33 and a central portion of the reflection surface 34. As a result, an indirect wave, which impinges obliquely on the side wall of the measurement chamber 32 and propagates along the side wall, is reflected from the bottom surface of the depression 34a and propagates.

Abstract: A disc playback apparatus for playing back a disc on which data have been recorded under a CLV control is provided with a CLV control section for performing a CLV control, a speed comparator and a reference clock generator for performing a CAV control, a changeover switch for switching between the CLV control and the CAV control, and a CPU for setting a switching point of the changeover switch and controlling the switching of the changeover switch. According to another aspect of the invention, switching is made between a playback with a CLV servo control and a playback with a CAV servo control in accordance with the reproduction scanning position in the disc radial direction. In particular, a difference between disc rotation speeds at the disc innermost and outermost tracks is made smaller than that in a case where a playback is performed at a specific linear velocity over the disc entire area.

Abstract: A recording and/or reproducing apparatus in which a recording medium contained in a holder is rotated and driven and a signal is read from or written to the recording medium. In the chassis employed as a base of the recording and/or reproducing apparatus, or in the holder for containing a recording medium, a strengthening rib having a stepped section is formed.

Abstract: A non-aqueous electrolyte secondary battery comprises a negative electrode having an active material comprised of lithium or a material capable of absorbing and releasing lithium, a lithium ion conductive non-aqueous electrolyte, and a positive electrode. The positive electrode active material is comprised of a composite represented by composition formula Li.sub.a R.sub.b L.sub.c M.sub.d O.sub.2 where R is one or more metalloid elements selected from boron B and silicon Si, L is at least one element selected from metals and metalloids of Groups IIIA and IVA of the periodic table, alkaline earth metals, and metals selected from the group consisting of Ti, Mn, Cu and Zn, M represents transition metal elements comprising at least Ni and Co, R, L and M are different, and a, b, c and d satisfy 0<a.ltoreq.1.15, 0.85.ltoreq.b+c+d.ltoreq.1.3, 0<b+c.ltoreq.0.5, 0<b and 0.ltoreq.c.

Abstract: A non-aqueous electrolyte secondary battery has a negative electrode, a positive electrode and a non-aqueous electrolyte with lithium ion conductivity. A composite oxide containing lithium represented by composition formula Li.sub.x Si.sub.1-y M.sub.y O.sub.z (where M is one or more kinds of elements selected from metals other than alkaline metals, and metalloids other than silicon, and x, y and z satisfy O.ltoreq.x, 0<y<1, and 0<z<2) is used as an active material for the negative electrode. The battery exhibits a negative active material with a lower and baser potential and a large charging/discharging capacity to produce a long cycle service life secondary battery which facilitates a large current charging and discharging and reduces deterioration due to excess charging and excess discharging.

Abstract: A non-aqueous electrolyte secondary battery has a negative electrode, a positive electrode and a non-aqueous electrolyte with lithium ion conductivity. A composite oxide produced from a metal or a metalloid and lithium represented by composition formula Li.sub.x MO (where M represents metals or metalloids other than alkali metals, and x satisifies 0.ltoreq.x) is used as an active material of one or both of the negative electrode and the positive electrode. The battery exhibits a large charging/discharging capacity and a high energy density together with smaller polarization (internal resistance) on charging and discharging which facilitates a large current charging and discharging with a long cycle life and reduces deterioration due to excess charging and excess discharging.

Abstract: A non-aqueous electrolyte secondary battery has a negative electrode, a positive electrode and a lithium ion-conductive non-aqueous electrolyte. A silicon oxide or a silicate containing lithium is used as the negative electrode active material. The potential of the negative electrode active material is low, the charge and discharge capacity in a base potential region of 0-1 V with respect to metallic lithium is large, and the polarization (internal resistance) during charge and discharge is small. A secondary battery having a high voltage and a high energy density is obtained in which large current charge and discharge characteristics are facilitated, the deterioration due to excessive charge and excessive discharge is reduced, the cycle life is long and the reliability is high.

Abstract: A nonaqueous electrolyte secondary battery uses lithium or a substance capable of absorbing and releasing lithium as a negative active material of a negative electrode, and uses a layer-like composite oxide of the formula Li.sub.x M.sub.y L.sub.z O.sub.2, where M is one or more transistion metal elements selected from Groups IIIB, IVB, VB, VIB, VIIB and VIII of the periodic table, L is one or more elements selected from nonmetal, metalloid and semimetal elements selected from Groups IIIA, IVA and VA of the periodic table, alkaline earth metal elements and metal elements of Zn and Cu as a positive active material constituting a positive electrode. The polarization (internal resistance) at the time of charging and discharging is reduced and an effective charging-discharging capacity is enhanced. Charging and discharging at a large current become easy, and a cycle deterioration is improved.

Abstract: A non-aqueous electrolyte secondary battery has a negative electrode, a positive electrode and a non-aqueous electrolyte with lithium ion conductivity. A composite oxide produced from a metal or a metalloid and lithium represented by composition formula Li.sub.x MO (where M represents metals or metalloids other than alkali metals, and x satisifies 0.ltoreq.x) is used as an active material of one or both of the negative electrode and the positive electrode. The battery exhibits a large charging/discharging capacity and a high energy density together with smaller polarization (internal resistance) on charging and discharging which facilitates a large current charging and discharging with a long cycle life and reduces deterioration due to excess charging and excess discharging.