Abstract: A sub-miniature power amplifier for hearing aids configured to be completely self-contained and to fit within the user's ear features a Class D amplifier stage providing a peak-to-peak output voltage greater than the power supply voltage. By configuring all signal elements as digital units, circuit balance is readily maintained. A substantial economy of battery drain is achieved while preserving a low value of distortion at low signal levels. Oscillator frequency is governed by a single resistance element. The amplifier and an optional efficiency-improving inductor can be accommodated entirely within the residual volume of the motor chamber of a state-of-the-art earphone housing. Pulse feedback networks are provided to achieve positive stable latching of each output pulse throughout its duration without producing significant pulse duration distortions.

Abstract: In a planar loudspeaker structure comprising planar membrane for forming a diaphragm on which a voice coil of a conductor pattern is formed, and a magnetic circuit for supplying a DC magnetic flux which crosses the voice coil, the conductor pattern includes first and second zigzag conductor pattern portions which are juxtaposed on substantially the entire area of the membrane and connected in series. Opposite ends of the series connection of the first and second conductor pattern portions are respectively connected to first and second terminals for receiving a low-band component of an input audio signal. A high-band component of the input signal is applied to a third terminal connected to a junction between the first and second conductor pattern portions and supplied only to the second conductor pattern portion.

Abstract: An image sensing device permits stable black level control by including therein image sensor driving circuit arranged to form an idle read signal immediately after each line portion of output is produced from an image sensor. The device includes a circuit for holding the idle read signal during a horizontal blanking period. A clamping circuit is included for clamping the output of the holding circuit at a predetermined reference potential. Finally, a reference potential forming circuit is arranged to form a reference potential using the signal level of a light shielded part of the image sensor.

Abstract: An electronic camera of a type employing an optical low-pass filter to eliminate moire pattern effects wherein the overall size of the camera is reduced and an optimum shutter efficiency is obtained. The camera includes, in order, an objective lens, a retractable mirror, a focal plane shutter, and an image pickup device. The optical low-pass filter is positioned between the retractable mirror and the focal plane shutter. The arrangement avoids interference with the path of the retractable mirror and prevents an increase in the distance between the focal length shutter and the image pickup device.

Abstract: Apparatus for continuously determining the position of best focus of an objective lens and a system having a video output. The technique uses a transmissive plate of variable thickness located on one side of the field stop of the optical system associated with the video output. The plate covers the full vertical field of the system and covers on the order of 30 to 40 resolution elements in the horizontal direction. The plate is divided vertically into platelets of different thicknesses which are distributed in such a way as not only to cover the range of defocus of the system, but to discriminate against possible variations in scene content. The plate is placed outside the active area which will be displayed by the video; therefore the variations in thickness and in focus introduced by the plate are not displayed on the video, but are only used for the purpose of continuously determining the position of best focus.

Abstract: An audio reproduction apparatus utilizing a speaker, electrical battery, amplifier, and source of electrical signals having a case for supporting the same. The electrical battery and source of electrical signals are held in relation to one another within the case.

Abstract: A telephone ear piece lock is disclosed to prevent unauthorized use of a protected telephone instrument. The ear piece lock includes a rim mounting bracket that is permanently affixed near the receiver end of the telephone and has a flat arm radially outwardly extending therefrom. The arm is provided with a transverse slot for instrument locking purposes. A disc-like cover overfits the receiver end to function as a sound barrier when tightly held over the receiver end. A bent locking finger extends from the cover and is configured to insert through the bracket slot. The locking finger is provided with an opening to receive a portion of a portable lock therethrough, the lock serving to prevent removal of the cover from its shielding position over the telephone receiver end.

Abstract: A conference system comprises a conference circuit to which a plurality of participants are connected via terminals respective connecting circuits having input and output circuits, the signal from the output circuits being fed to the connecting circuit and signals from the conference circuit being fed lines to the input circuits. The conference circuit has summing amplifiers (10 to 13) whose inputs are connected to the outputs of the connecting circuits so that the output signals from the connecting circuits are algebraically summed. The signs of the signals to be summed are determined from the relationship E-S* S=O where E is the unity matrix and S* is the transposed complex conjugate matrix of S.

Abstract: A portable communication apparatus (10) for communication between a first person of normal hearing ability and a second person whose hearing is impaired is disclosed. The communication apparatus includes a first housing (12) enclosing a microphone and an amplifier, the first housing (12) being adaptable for being carried in a coat pocket or the like of the first person. The communication apparatus further includes a second housing (22) constructed and arranged to fit over the ear of the second person. The second housing (22) includes means for receiving electrical signals from the amplifier and converting the electrical signals into sound. An electrical connector (20) electrically connects the receiving means in the second housing (22) with the amplifier in the first housing (12) whereby the voice of the first person is amplified and transmitted to the receiving means in the second housing (22), thereby enabling the second person to hear the first person.

Abstract: Apparatus is described for restoring the original comprehension of sounds reaching a human ear, including direction, elevation and frequency. An enclosure surrounds the pinna of the ear to substantially exclude exterior sounds. First and second speakers are placed in a chamber, within the enclosure, anterior to the pinna, such that each transducer radiates to the entire pinna. The speakers are mounted on the inner surface of the anterior wall of the enclosure along a vertical line which is generally parallel to the vertical axis of the pinna. First and second microphones are mounted on the anterior surface of the enclosure also along a vertical line and are connected respectively to the first and second speakers through amplifying means. The speakers reproduce the received sounds and through the dissimilarities in the sound provide the hearer with the sense of the angular elevation of the source.

Abstract: A loudspeaker enclosure has a loudspeaker driver mounted on a surface of the enclosure such that the driver has an exposed front face to produce sound waves which are sought to be transmitted to a listening space exterior of the loudspeaker enclosure. A plurality of successive spaced limp or semi-limp non-porous pliable barriers are positioned in an opening between the interior and exterior spaces of the enclosure so as to relieve rear pressure of the loudspeaker driver while attenuating the rear sound waves and providing a damping effect on the loudspeaker driver.

Abstract: A piezoelectric loudspeaker having a bending mode piezoelectric diaphragm mounted on a diaphragm stretched across a frame, the piezoelectric diaphragm being supported at its central portion to a support provided at the frame, so that the central portion of piezoelectric diaphragm is stationary free from vibrations, thereby being higher in a sound pressure level and smaller in acoustic distortion than the conventional loudspeaker.

Abstract: A generalized signal processing device for use as a hearing aid generates and modifies signals representative of acoustic patterns in a physiologically compatible manner which enables persons suffering from various auditory pathologies to recognize sound patterns including human speech.

Abstract: The invention relates to a structural member made from a metallic material aving an upper surface exposed to dangers of electric charge accumulations during operation in an apparatus such as a high vacuum apparatus operating with a charge carrying beam wherein the upper surface is formed with a conductive or semiconductive compound of the metallic material which is also present in the body of the structural member and is in electrical contact with the body of the structural member, thereby preventing undesirable charge accumulation on the surface.

Abstract: In the illustrated embodiments, the signals to be transmitted are converted into electrical signals and are divided by means of filters into a plurality of frequency bands. The envelopes of the signals coming out of the filters are then employed for the modulation of tones. Finally, the original tones and the modulated tones are supplied to the hearing-impaired person as an audio signal. To this end, the disclosure provides that the original signal to be transmitted is transmitted together with the modulated tones, and that the ratio of the volumes of the original tones and those of the modulated tones is set to a ratio which is comfortable for the hearing-impaired person. The transmission of the modulated tones is at least partially interrupted for voiced sounds. Standard ear sets or implanted devices with direct electrical transmission of the signals to the auditory nerve can be employed for transmission to the hearing-impaired person.

Abstract: A roller for transport and/or guidance of flexible webs or sheets of radiation-sensitive material has a grounded shaft and an antistatic cylindrical member which is coaxial with and surrounds the shaft and has a web- or sheet-contacting cylindrical peripheral surface. The cylindrical member consists of hard polyvinyl chloride, fine crystalline polyamide, polypropylene, polyethylene or a mixture of two or more such plastic materials. Pulverized silver or another pulverulent metal is embedded in the material of the cylindrical member. If the roller is rather long, the cylindrical member surrounds a hollow cylindrical metallic core whose end portions confine inserts which surround the respective end portions of the shaft.

Abstract: A speaker in which a voice coil bobbin (4) is connected through a mechanical filter to vibrating members (11, 14) for limiting the reproducing frequency band in predetermined range by the mechanical filter, and a speaker system employing the speaker. A pneumatic suspension V is used as the mechanical filter to eliminate the variations in the reproducing frequency band even for long term usage.

Abstract: A method of driving a valve in an injector for an internal combustion engine which intermittently injects liquid fuel by the valve reciprocally moving by attraction force of a solenoid coil and repulsive force of a spring and an apparatus for carrying out the method. An armature secured to the valve to be attracted by the solenoid coil and/or an iron core of the solenoid coil is made of a permanent magnet. The pulse shape of an electric current to be applied to the solenoid coil is made in the form of a stepped wave in which the electric power in the initial stage of application is larger than that in the later stage. An inverse pulse for inversely exciting the solenoid coil is formed to give the permanent magnet of the armature repulsive force upon fall of the pulse wave of the electric current applied to the solenoid coil.

Abstract: A demagnetizing apparatus for removing residual magnetism in the body of an automobile which is equipped with a magnetic bearing indicator. A first and a second coil are wound around a substantially flat frame of a non-magnetic material to produce respectively a fixed d.c. magnetic field and a controllable a.c. magnetic field in orthogonal directions with each other and along flat surfaces of the substantially flat frame. The substantially flat frame with coils is positioned adjacent to but spaced from a body portion such as a roof, door or floor of the automobile, so that the d.c. magnetic field produced by the first coil cancel the external magnetic field caused by the terrestrial magnetism. The a.c. magnetic field is controlled to be intensified and weakened alternately thereby to remove the residual magnetism of the body portion without being influenced by the external magnetic field.

Abstract: A pair of demagnetizing coils, or more than two, and the article to be demagnetized is put in the coils. The demagnetizing is done by reversing the polarity in a series of steps in a cycle, and the current reduced in successive steps, to a point at or near zero. The cycle can be varied as to time period, and the number of steps within a cycle varied. The applied initial voltage can be adjusted or predetermined as to maximum value, with corresponding current values, and the number of steps predetermined within the cycle independently of the maximum voltage. The apparatus can be set in manual mode, wherein the cycle timer period and number of steps can be independently set, and to automatic mode, wherein the cycle time and number of steps are directly correlated.