Ricoh Company, Ltd.

Isamu Shibata

Kazuyuki Shimada

Ikuo Maeda

Takahiro Asai

Yutaka Kaneko

Masanori Horike

Hiroshi Gotoh

Nobuaki Kubo

Akio Kojima

Takeo Yamaguchi

Masao Yoshikawa

Susumu Imakawa

Kenichirou Asada

Yoshiaki Kanmoto

Iwao Hamaguchi

Kiyoto Nagasawa

Tatsuaki Sakurai

Kaoru Teramura

Isao Yamada

Susumu Imagawa

A servo method in a multibeam optical pickup in which, at the time of a recording mode, a record information is confirmed and reproduced by a beam for reproduction while the record information is written by a beam for record, and the record information is reproduced by the beam for reproduction at the time of a reproducing mode, comprises the steps of detecting a focus servo signal and a track servo signal with respect to each of the beams for record and reproduction reflected by an optical disk; performing focusing and tracking operations based on the focus servo signal and the track servo signal provided by the beam for record at the time of the recording mode; and performing the focusing and tracking operations based on the focus servo signal and the track servo signal provided by the beam for reproduction at the time of the reproducing mode. In another servo method, the focusing and tracking operations may be performed according to the recording and reproducing modes. An optical pickup comprises a detector for detecting respective track error signals with respect to the preceding and subsequent beams; a tracking control device for performing a tracking servo control by the track error signal detected based on one of the beams; and a tangential control device for performing a tangential servo control by the track error signal detected based on the other of the beams.

Multibeam optical pickup and servo method thereof

A high dielectric polymeric optical recording medium for recording information by heating the portions of the recording medium corresponding to the information to be recorded by being exposed to a beam of light, followed by the application of a reverse electric field to the recording medium, thereby selectively reversing the polarity of the heated portions in the recording medium, is disclosed, which comprises a high dielectric polymeric recording layer containing a high dielectric polymeric composition comprising a high dielectric polymeric material and a nonionic dye serving as a light-absorption agent which is compatible with or dispersible in the high dielectric polymeric material.

High dielectric polymeric optical recording medium

An apparatus for handling an optical card which is generally rectangular in shape and formed with a first plurality of circular, concentric recording tracks and a second plurality of arc-shaped, concentric recording tracks in each of a pair of sectors defined by a pair of hypothetical diagonal lines of the card and located outside of the first plurality of circular, concentric recording tracks. An optical pick-up is moved to a desired track first by a coarse seek operation which uses the difference between a selected count and the count from a linear sensor, and a fine seek operation which uses the sum of a track correspondence voltage and a track error signal.

Seek and track control for a rectangular optical card handling apparatus

A semiconductor laser control apparatus for controlling an optical output of a semiconductor laser to a predetermined value comprises a switching part coupled in series with the semiconductor laser and controlled by an N-bit image signal, N constant current supply circuits coupled in parallel to each other and in series with the switching part for supplying currents to the switching part so that a driving current is supplied to the semiconductor laser from the switching part, a detector for detecting the optical output of the semiconductor laser and for outputting a detection signal indicative of the detected optical output, and a control part responsive to the detection signal from the detector for controlling the driving current by controlling the N constant current supply circuits so that the optical output of the semiconductor laser becomes the predetermined value.

Semiconductor laser control apparatus

A system for controlling the operation of a semiconductor laser is provided. In one aspect of the present invention, a switching element, which is turned on and off in accordance with a signal modulated with image information, is connected in series with the semiconductor laser for controlling the operation thereof. In another aspect of the present invention, a semiconductor laser control system includes a photodetector for detecting the intensity of a laser beam emitted from the laser, a comparator for comparing the detected intensity with a predetermined refence intensity, an up/down counter which changes its count depending on the result of the comparison at the comparator, and a laser driver which supplies a driving current to the laser as modified by the count of the counter. A reset circuit is provided to reset the counter when at least the laser driver is powered up with a predetermined supply voltage. In addition, the laser driver is so structured that the supply of the driving current to the laser is disconnected for a predetermined time period after the power up thereof.

Semiconductor laser control circuit

A laser beam emitting apparatus includes a semiconductor laser, a photodiode for detecting the intensity of the laser beam, an amplifier for amplifying the detection signal from the photodiode, and a variable resistor connected to the amplifier for adjusting the gain of the amplifier. In one embodiment, these elements are provided in a unit structure so that the adjustment of the gain of the amplifier can be carried out in advance. In another embodiment, a collimating lens for collimating the laser beam emitted from the laser is also provided in the same unit. In another embodiment, a single-piece support is provided to support the semiconductor laser, the collimating lens, and an aperture plate formed with an aperture for shaping the collimated laser beam. As a modification, the single-piece support can be made dual in structure while maintaining the structural integrity of the support.

Laser beam emitting apparatus

A scanning clock generating device for an optical scanner which scans a selected surface by a light beam to write optical information or read image information. The scanner scans the surface by a light beam which is deflected at a constant or a non-constant angular velocity and without resorting to an F-theta lens. The scanning clock generating device generates a scanning clock the frequency of which is continuously variable responsive to changes of scanning velocity on the surface to be scanned.

Scanning clock generating device for optical scanner

An optical scanner for use with a laser printer, a laser display or the like includes an optical deflector for directly scanning a photoconductive drum with a beam which is emitted from a semiconductor laser and to be focused as a minute spot on the drum. The frequency of an image scanning clock is continuously varied as an approximation to scanning speeds of a spot which is produced by the deflector. The intensity of the beam is controlled by an intensity control circuit.

Optical scanner without extra convergent lens

A semiconductor laser output intensity control device is provided in a laser beam scanning system, such as a laser printer. A laser beam emitted from a semiconductor laser is modulated by image information and scanned across a photosensitive member for forming an image thereon. The present output intensity control device employs an up/down counter whose count determines the level of driving current to be applied to a laser driver which drives the semiconductor laser. The up/down counter changes its count either up or down depending on the magnitude of the output intensity of the laser beam as compared with a reference level. The present device includes a control circuit which prevents the power setting operation of the laser from taking place during a scanning time period in which the photosensitive member is scanned by the laser beam.

Semiconductor laser output control device

A device detects the radiating output from a semiconductor laser and compares a detected signal with a reference signal in a comparator. An up/down counter is controlled an output signal from the comparator to supply the semiconductor laser with a current proportional to a count output from the up/down counter. The current supplied to the semiconductor laser is controlled and held so as to equalize the input signals to the comparator at all times.

Device for controlling the radiating output of a semiconductor laser

A light deflector for use in a laser printer, for example, is composed of a motor having a drive shaft and a light reflecting member such as a rotating multiple-surface mirror or a hologram. The motor is subjected to magnetic field ripples the number of which is equal to a multiple by an integer of the number of light reflecting surfaces of the light reflecting member.

Light deflector

First and second optical systems each comprise identical converging lenses which focus light images of an object onto identical photosensor arrays, the lenses being parallel. First and second mirrors reflect the light images from the respective lenses onto the respective arrays. The first mirror is fixed whereas the second mirror is rotatable. Where the second mirror is rotated to a position where the light images on the arrays are identical, the distance to the object is a function of the position of the second mirror which is predetermined by triangulation. As the second mirror is rotated through a predetermined range the arrays are strobed a predetermined number of times to produce analog signals having magnitudes corresponding to incident light. The respective analog signals are subtracted and the resulting difference signals compared with a previously minimum value. Each time the arrays are strobed a counter is incremented. However, when a difference signal has a value lower than the minimum value (a previous difference signal), it becomes the new minimum value and the counter is reset. The count in the counter after the arrays are strobed the predetermined number of times corresponds to the position of the second mirror when the minimum value was sensed and thereby the distance to the object. A servo system may be provided to position a camera lens in accordance with the count in the counter and thereby automatically focus a camera.

Optoelectronic sensing apparatus

In the control system, the motor is supplied power in the form of a pulse train. The width of each pulse of the pulse train is modulated through the comparison between a reference voltage and the counter e.m.f. of the motor immediately prior to feeding of each pulse of the pulse train into the motor.

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Fuchu, Japan

Isamu Shibata