Abstract: An attenuation-amount adjusting circuit includes: a light irradiating unit that alternately irradiates a laser beam of a writing level and a laser beam of a readout level on an optical disk that has a groove formed by a wobble pattern and plural markers indicating physical positions in the groove; a light receiving unit that receives reflected light of the laser beam irradiated on the optical disk and converts the reflected light into a reproduction signal; and a writing-waveform attenuating unit that attenuates an amplitude level of a writing waveform corresponding to the reflected light of the laser beam of the writing level in the reproduction signal according to a position from a rising edge of the writing waveform.

Abstract: Various embodiments of the present invention provide systems and methods for reduced latency feedback in a data processing system. For example, some embodiments provide a data processing system that includes a variable gain amplifier, a processing circuit, a data detector, and an error signal calculation circuit. The variable gain amplifier amplifies a data input signal and provides an amplified signal. The processing circuit generates a signal output corresponding to the amplified signal, and includes a conditional multiplication circuit. The conditional multiplication circuit conditionally multiplies the signal output by a gain correction signal and provides the result as an interim output. The data detector applies a data detection algorithm to the signal output and provides an ideal output. The error signal calculation circuit generates a gain correction signal based at least in part on the interim output and a derivative of the ideal output.

Abstract: A variable gain amplifier (203: VGA) for amplifying an amplitude of a signal extracted by a pickup (202), an A/D converter (204) for converting the amplified signal into digital, and an amplitude detecting circuit (206) for detecting amplitude information from the digital information, are provided. A gain control circuit (205) for calculating a control value for the VGA (203) is calculated from the detected amplitude information, and an envelope generating circuit (207) for executing an operation of absorbing transfer characteristics of the VGA (203) from the control value for the VGA (203) and the amplitude information, are provided to generate an envelope extracted by the pickup (202). When the characteristics of the VGA (203) vary, a degree of the variation is calculated from the amplitude information of the signal extracted by the pickup (202) and amplitude information obtained by fixing the control value for the VGA (203), and characteristic correction is executed.

Abstract: A variable gain amplifier (203: VGA) for amplifying an amplitude of a signal extracted by a pickup (202), an A/D converter (204) for converting the amplified signal into digital, and an amplitude detecting circuit (206) for detecting amplitude information from the digital information, are provided. A gain control circuit (205) for calculating a control value for the VGA (203) is calculated from the detected amplitude information, and an envelope generating circuit (207) for executing an operation of absorbing transfer characteristics of the VGA (203) from the control value for the VGA (203) and the amplitude information, are provided to generate an envelope extracted by the pickup (202). When the characteristics of the VGA (203) vary, a degree of the variation is calculated from the amplitude information of the signal extracted by the pickup (202) and amplitude information obtained by fixing the control value for the VGA (203), and characteristic correction is executed.

Abstract: There is provided a light receiving circuit capable of preventing an output variation of the light receiving circuit due to a change in ambient temperature with a simple configuration. The light receiving circuit is provided with a photodiode 4 for LD power monitoring and an I-V amplifier 5 connected with a feedback resistor 13, wherein a light receiving section 16 of the photodiode 4 is covered with a protective film 19. Temperature dependences between a light transmittance of the protective film 19 in accordance-with a shift of a wavelength of a laser beam due to a change in ambient temperature, and a resistance value of the feedback resistor 13 are set in such a way that they may be mutually compensated and an output voltage from the light receiving circuit may be constant for a temperature change.

Abstract: A photocurrent amplifier circuit is capable of selectively amplifying one or more of photocurrents which are respectively obtainable from plural receiving devices, and can be realized to have a small size. The photocurrent amplifier circuit includes: light receiving devices; amplifier devices associated with the light receiving devices; device selector switches which apply input voltages, which inactivate the amplifier devices, to the associated amplifier devices; and a differential amplifier circuit having an inverting input unit configured by the amplifier devices which are connected in parallel. The inputs of the amplifier devices and the output of the differential amplifier circuit are connected by gain resistances. The differential amplifier circuit amplifies, into voltage signals, photocurrents flowing from the light receiving devices which respectively associated with the gain resistances.

Abstract: A magnetic storage medium is read by incident polarized light and reflected outgoing light defining a common plane. The polarized incident light preferably has a polarization vector at 40.degree. to 50.degree. to this plane and at the storage medium, the magnetization is in a direction perpendicular to the plane. The preamplified output signal V.sub.M from the photodiode transducing the outgoing light beam has a fixed value V.sub.O subtracted therefrom where V.sub.O is a function of the sensitivity and resolving power of the electronic circuitry. The signal V.sub.M -V.sub.O is then amplified and processed to represent the stored data.

Abstract: An optical disc reproduction apparatus is disclosed including a device for detecting a maximum audio signal level recorded on the optical disc. A first course-search is effected of the entire optical disc to detect a first location on the optical disc in which a maximum value of a recorded audio signal is located. A second fine-search of the optical disc is effected within a region extending in opposite directions from the location on the optical disc detected during the first course-search. During the second fine-search operation, a second location on the optical disc is located in which a maximum value of the recorded audio signal level is located. Then, audio signals are reproduced repetitiously in the vicinity of the second location detected during the second fine-search operation.

Abstract: A disc playback device capable of automatically adjusting the tone volume of a signal reproduced from a disc comprises a disc identifying circuit for identifying a disc loaded in the device, a tone volume setter for setting the tone volume of a signal reproduced from the disc, a memory for storing tone volume data for each disc set by the tone volume setter together with disc identifying data provided by the disc identifying circuit, and an automatic tone volume adjusting circuit for reading out set tone volume data corresponding to data of the identified disc from the memory when the disc has been loaded in the device and automatically adjusting the tone volume setter to the set tone volume. Data representing an optimum volume for each disc determined by the listener and disc identifying data are stored in the memory.

Abstract: An information reproducing apparatus which enables regulation of sound volume levels of signals reproduced from a multiple-audio recording medium in which one of a plurality of audio information signals may be reproduced in conjunction with video information. The multiple-audio signals are recorded on a surface of a video disk, along with the video information. A code signal indicative of presence of multiple-audio information also is recorded, and is detected by code reading circuitry in the apparatus. Operation of changeover circuitry is controlled in accordance with the presence or absence of the code signal, and also in accordance with operation of a microphone in a microphone mixing mode.

Abstract: A rotary head type reproducing apparatus having a plurality of rotary transmitters which respectively receive signals reproduced from a record bearing medium by a plurality of rotary heads is arranged to eliminate any cross-talk between the rotary transmitters by adjusting the levels of signals produced from these transmitters relative to each other and then by performing a computing operation on the adjusted signal levels.

Abstract: An audio signal amplifier for an electromagnetic transducer, comprises a transformer which has a primary winding coupled to the electromagnetic transducer for receiving an output audio signal from the electromagnetic transducer and a secondary winding for producing a transformed audio signal as an output. The transformer has a turn ratio of the primary winding and the secondary winding which is selected to n:1, where n is a real number greater than 1. The audio signal amplifier further comprises a current-voltage conversion circuit which is coupled to the secondary winding of the transformer for converting an audio signal current from the secondary winding into an audio signal voltage.

Abstract: A method for correcting higher order distortion introduced in a complex multifrequency waveform by an element which introduces signal-induced nonlinearities uses a replica of the non-linear element as a part of a high gain electronic feedback circuit between the output and an input of an amplifier. The replica of the non-linear element receives the multifrequency waveform, and is driven to duplicate the non-linear effects, which are used to generate a compensating voltage which is compared to the voltage obtained from the non-linear device. The resultant difference voltage after the comparison and amplification is then closer to the original signal. Thus, in an audio system for example, distortions which are audibly apparent to the human ear but so small they are immeasurable by instrumentation can be eliminated or minimized by employing a number of replicas in the same fashion.

Abstract: A small signal amplifying circuit suitable for use in a system such as a disc player-amplifier system in which metal contact portions such as connectors are used between a signal source and an amplifier. The small signal amplifying circuit according to the invention is an improvement of a circuit which is designed to eliminate distortion caused by the metal contact portions by transmitting a signal in a state in which the signal is superposed on a direct current. The circuit according to the invention includes a first transistor provided in a signal source and a second transistor provided in an amplifier which constitutes a differential amplifier with the first transistor. By negative feeding-back the output of the amplifier to the base of the second transistor, distortion factor, signal-to-noise ratio and stability in characteristics are remarkably improved.

Abstract: The preamplifier has a first stage or section of low or unity gain, such as an emitter-follower circuit, which also isolates the preamplifier from impedance variations of the cartridge, and with a bandwidth for greater than the audio range to reproduce signals with a very high amplitude, rapidly changing wavefront without slew or amplitude overload distortion. A RIAA high frequency de-emphasis network is coupled between this first stage or section and a second amplifier section. A RIAA low frequency emphasis network is preferably placed in a negative feedback circuit of the latter amplifier section where the feedback circuit does not contain the high frequency components filtered out by the high frequency de-emphasis network. The second amplifier section need not have the bandwidth of the first amplifier stage or section.

Abstract: A multi-function phonograph tone arm control system for a low-friction air bearing supported linear-travelling tone arm system is disclosed. Positive horizontal linear positioning is accomplished by means of an electromagnetic force producing system in which opposing linear forces may be balanced at any point along the path of straight-line travel of the tone arm to position the tone at any desired location. A separate electromagnetic force producing system is utilized to control the vertical pivoting of the tone arm including the pressure of the stylus on a phonograph record. A further motion damping means is provided to stabilize the motion of the tone arm and prevent any unwanted vibration of the tone arm. A means for automatically shutting off the system at the end of a record is also provided.

Abstract: A muting switch for co-operation with the phono sockets of a record player to short circuit the leads from the pick-up, which are connected to the phono socket, at all times except when a record is being played.