Kabushiki Kaisha Suwa Seikosha

Seiko Epson Corporation

Seiko Epson Kabushiki Kaisha

Seiki Epson Corporation

Shigeru Kogure

Masatoshi Yonekubo

Eishi Momosaki

Minoru Inoue

Takashi Takeda

Osamu Yokoyama

Hidefumi Sakata

Mamoru Sugimoto

Hideaki Iwano

Akira Aoyama

Tetsuya Seki

A small and inexpensive optical head for detecting a recorded signal, a focusing error signal and a tracking error signal, and an optical memory device utilizing the optical head. A diffraction device (103) is provided having two chirped grating regions (103A, 103B) for dividing a light beam from an optical recording medium (105) and directing the divided beams toward four band-shaped photoelectric transducers (106) and an astigmatism generator formed by the diffraction device (103) and a positive lens (102). The four photoelectric transducers are positioned in a plane inclined with respect to the optical axis of zero-order diffraction light, and the longitudinal axes of each of the band-shaped photoelectric transducers are radially arranged relative to the optical axis.

Optical head and optical memory device

A magneto-optic recording medium including a transparent substrate and a non-oxide dielectric layer formed thereon is provided. The dielectric layer includes a first dielectric material of the type which exhibits cracks running in a generally radial direction when deposited on a surface and which is designated dielectric Group A and a second dielectric material which exhibits cracks running in a generally tangential direction when deposited on a surface and which is designated dielectric Group B. The dielectric layer may be separate layers or a mixture of the two dielectric materials.

Optical recording medium

A magneto-optical signal read-out system for a magneto-optical player in which the polarized plane of linearly polarized incident light is rotated when the incident light is reflected by or passes through a magneto-optical medium having tracks thereon and the rotation angle of the polarized plane is utilized as an information signal. The read-out system includes a first analyzer, a second analyzer and a photo detector divided into first and second photo detector sections. A differential amplifier receives output signals from the first and second photo detector sections and produces a detected signal representative of the difference between the first and second output signals to reduce in-phase noise in the detected signal.

Magneto-optical signal read-out system using divided photodetector

An apparatus for reading data to and from a moving magneto-optical recording medium includes a carriage which is moved across data tracks contained in the medium. Optics for focusing a spot of light on the medium and a mechanism for fine tracking of the spot on a selected track are carried on the carriage and are movable independently of the carriage in response to separately amplified servo signals which are derived from light which is reflected from the spot of light on the data-containing track.

Optical read/write device

A mode coupled tuning fork resonator is cut at a preferred angle and with selected length, width, and thickness to produce a resonator having a highly favorable frequency-temperature characteristic over a wide range of operating temperatures. The frequency-temperature characteristic can be expressed in a Taylor's expansion dominated by the fourth power term.

Mode coupled quartz crystal tuning fork

A mode coupled tuning fork type quartz crystal resonator is mounted to a plug using support members of selected contour and dimensions to prevent acoustic energy loss from the plug and to avoid reduction in Q factor. A bend of 180 degrees in the support member and controlled length are factors in isolating fundamental and first overtone vibrations in flexure and fundamental torsional vibrations so as to reduce energy loss, maintain stable oscillation and improve the Q factor. A laterally extended base portion and/or tapered ends of the tuning fork arms enhance the beneficial results.

Mode coupled notched tuning fork type quartz crystal resonator

A mode coupled tuning fork type quartz crystal vibrator utilizing two different vibrational modes is provided. The vibrator includes at least one electrode on each tuning fork arm for adjusting the resonant frequency of the main vibration and an electrode for adjusting the frequency-temperature characteristic of the vibrator. The main vibration is in the flexural mode (F.sub.1) and the sub-vibration is in the torsional mode (T.sub.0). The resonant frequency of the first overtone in the flextural mode is designated by f.sub.F and the resonant frequency of the fundamental vibration in the torsional mode is denoted by f.sub.T. The difference between f.sub.F and f.sub.T defined as .DELTA.f=f.sub.F -f.sub.T determines the frequency-temperature characteristics of the mode coupled vibrator. The electrodes for adjusting f.sub.F are substantially triangular in shape and the electrodes for adjusting f.sub.T are substantially rectangular in shape. These electrodes are disposed at positions near the top of each tuning fork arm and on both principal surfaces of the vibrators. The resonant frequencies are adjusted by removing a portion of electrode material or adding a strip of metal to the electrode. Preselected oscillation frequency and frequency-temperature characteristics in the form of a cubic curve at ambient temperatures are obtained by first adjusting .DELTA.f to a preselected value .DELTA.f.sub.O and then adjusting f.sub.F to a preselected value f.sub.F0 at the same time maintaining .DELTA.f at the value .DELTA.f.sub.0.

Mode coupled tuning fork type quartz crystal vibrator and method of

A tuning fork type quartz crystal vibrator has electrodes formed on its surfaces with the electrodes being divided into separated portions along the length of the tuning fork arms such that opposite electric fields and charges are juxtaposed in the same arm. Dividing the electrode at a location along the tuning fork arms where strains induced during vibration reverse direction, enhances the ability to induce vibrations. A low resonant resistance and high capacity ratio are provided for an overtone frequency of flexual vibrations.

Electrode for tuning fork type quartz crystal vibrator

Cutting a quartz tuning fork crystal vibrator at a preferred angle and with a thickness which establishes a close coupled relationship between the flexural and torsional modes of vibration of the arms or tines produces a vibrator having a highly favorable cubic frequency temperature characteristic at predetermined frequencies. Weight added to the ends of the vibrating tines reduces the frequency of both flexural and torsional vibration, whereas weight added at nodal points in the flexural vibration primarily reduces only the torsional vibrational mode. Accordingly, a wide range of frequency adjustments is possible. Deviations from the desired crystal operating frequency due to manufacturing variances are adjustable by sequential weight modifications while the desirable cubic temperature characteristic is retained. High accuracy over a wide temperature range permits operation in oscillator circuits at relatively low frequencies and with attendant low power consumption. Close coupling between vibrational modes occurs when the difference between the flexural and torsional frequencies is .ltoreq.0.15 of the flexural frequency. The principles for dimensioning the crystal, and adjusting thickness and weight, are applicable to both fundamental and overtone frequencies.

Coupled mode tuning fork type quartz crystal vibrator

A conventional tuning fork type quartz crystal resonator has mainly two vibration modes. They are fundamental vibration mode and overtone having the resonance frequency six times as much as the frequency of fundamental vibration. These two vibration modes have similar high quality factors. When this resonator is put to practical use, there are instances where it oscillates in undesirable mode of vibration. Accordingly, in this invention, concave portions are provided at the tops of resonator in order to prevent it. It is the most effective in case that concave portions are provided in the region of 0.65 to 0.85 from roots of arms.

Growing community of inventors

Suwa, Japan

Shigeru Kogure