Discovision Associates

Randolph Scott Crupper

David L Schell

Kurt W Getreuer

David E Lewis

Marvin B Davis

Leonardus J Grassens

Leonardus I Grassens

An analog to digital circuit assembly includes a circuit for multiplexing a reference voltage input of an analog to digital converter to produce alternating normalized and referenced digital outputs of an analog signal input at a rate controlled by a sampling clock which includes a switch including first and second inputs, an output, and a control input for alternately connecting the first and the second inputs to the output, the output being applied to the reference voltage input. An information detection device having a detection output and a servo mechanism that controls operations on detected information is provided in conjunction with a signal summing circuit, a direct current voltage reference, a control clock connected, a servo error signal circuit having a servo error signal output and input, a sampling clock, and a processing circuit having an input connected to a digital output of the analog to digital converter and an output for controlling the servo mechanism. The analog to digital circuit assembly is also implemented in an optical disc system for improved operation thereof.

Analog to digital converter assembly for normalizing servo error signals and multiplexing reference voltage inputs and digital outputs and improved optical drive system including same

An analog to digital circuit assembly for use in an optical information includes a circuit for multiplexing a reference voltage input of an analog to digital converter to produce alternating normalized and referenced digital outputs of a plurality of analog signal inputs at a rate controlled by a sampling clock which includes a switch including first and second inputs, an output, and a control input for alternately connecting the first and the second inputs to the output, the output being applied to the reference voltage input. An information detection device having multiple detection outputs and having at least one servo mechanism that controls operations on information being detected is provided in conjunction with a signal summing circuit, a direct current voltage reference, a control clock connected, a servo error signal circuit having a servo error signal output and multiple inputs, a sampling clock, and a processing circuit having an input connected to a digital output of the analog to digital converter and an output for controlling at the least one servo mechanism.

Analog to digital converter and assembly for use in optical drive system to normalize servo error signals and multiplex reference voltage inputs and digital outputs

An optical drive system includes an optical assembly, a light source, a lens positioned to direct light between the optical assembly and an information storage medium or disc, and an actuator suspending the lens. A photodetector is disposed in a path of returning light to measure light received from the medium. A monitoring circuit is provided to monitor a Quad Sum signal associated with return light. A first servomotor is employed to move the lens in a tracking direction and to move the lens during focus capture while system circuitry searches for a maximum Quad Sum signal. A second servomotor is employed to move the lens in a focusing direction. A first electronic circuit is provided to control the first and second servomotors. A servo error circuit is coupled to the first electronic circuit and the photodetector to determine when return light exceeds a predetermined value, to search for a first zero crossing, and to indicate to the first electronic circuit to close focus by the second servomotor when the Quad Sum signal exceeds a predetermined amplitude. A focus capture method for use in the system includes impinging light upon the disc, moving the lens, monitoring the Quad Sum signal, moving the lens while looking for a maximum Quad Sum signal, monitoring light received from the disc, determining when the light is above a measured peak value, searching for the first zero crossing, determining when the Quad Sum signal exceeds a predetermined amplitude, and closing focus at the predetermined amplitude.

Optical disc system having servo motor and servo error detection assembly operated relative to monitored quad sum signal and focus capture method for use in same

A mechanical isolation apparatus suited for mitigating the effects of undesired mechanical forces upon disc drive system components, such as those found in compact disc, laser disc, magneto-optical player/recorder devices and similar devices. Component members are provided for mitigating the effects of compressive forces, vibration isolation, and thermal expansion, and may include compression ribs mounted on a housing for absorbing compressive forces. The housing is preferably adapted to fit on the end of a pole piece assembly. A crash stop may also be provided as a shock absorbing bumper and isolator to prevent a moving carriage from crashing into a solid surface. The compressive ribs and the crash stop are made of a material that exhibits minimum creep, such as a silicon rubber, polyurethane, or injection molded plastic.

Isolation apparatus for use in disc drive system to mitigate effects of

An optical drive system includes an objective lens subassembly for directing light from a light source toward an information storage medium. An amount of the directed lighted light is returned from the storage medium. An objective lens is disposed in the objective lens subassembly. A first servomotor moves, during focus capture, the objective lens to a first position, away from the first position toward the storage medium being read while looking for a maximum Quad Sum signal, and back away from the storage medium. An electronic control circuit is connected to the first servomotor. A servo error detector is coupled to the electronic control circuit and disposed in a path of light returning from the information storage medium. The servo error detector is implemented to determine when total light returned from the information storage medium exceeds a predetermined value, to search for a first zero crossing, corresponding to when the Quad Sum signal exceeds a predetermined amplitude, and to indicate to the electronic control circuit to direct close of focus when the Quad Sum signal exceeds the predetermined amplitude.

Optical drive system having servomotor operated relative to maximum quad

An optical drive system includes an optical assembly, a light source capable of transmitting light through the optical assembly, an objective lens positioned to direct light between the optical assembly and a respective information storage medium, and an actuator suspending the objective lens for relative motion thereof with respect to the actuator. A photodetector is disposed in a path of returning light to measure return light received from the respective medium. A monitoring circuit is provided to monitor a Quad Sum signal associated with the return light. A first servomotor is employed to move the objective lens in a tracking direction relative to the actuator and to move the objective lens during focus capture relative to the respective medium being read while system circuitry searches for a maximum Quad Sum signal. A second servo motor is employed to move the objective lens in a focusing direction relative to the actuator assembly. A first electronic circuit is provided to control the first and second servomotors. A servo error circuit is coupled to the first electronic circuit and the photodetector to determine when the return light exceeds a predetermined value, to search for a first zero crossing determining when the Quad Sum signal exceeds a predetermined amplitude, and to indicate to the first electronic circuit to direct close of focus by the second servomotor when the Quad Sum signal exceeds the predetermined amplitude.

Growing community of inventors

Palmer Lake, CO, United States of America

Randolph Scott Crupper