Ricoh Company, Ltd.

Cirrus Logic Inc.

Takeo Wada

Koichi Suzuki

Takashi Mori

Katsuaki Miyawaki

Noriyoshi Tarumi

Makoto Obu

Toshiyuki Kawanishi

Yasuo Hirano

Masato Igarashi

Fuchio Takeda

Kazuhiro Nishido

A method and system retrieving data stored on a compact disk read only memory (CD-ROM) device using the constant angular velocity (CAV) reading technique. Unlike the constant linear acceleration (CLA) reading technique, in the CAV reading technique the data retrieval rates of the CD-ROM read head vary depending on the radius of the annular recording track that is being read. Data rates can be as much as 2.5.times. faster for the outer recording tracks compared to the inner recording tracks. The novel system utilizes a narrow capture band phase lock loop circuit in conjunction with a microcontroller which controls the center frequency supplied to the phase lock loop circuit. The microcontroller adjusts the center frequency of the phase lock loop circuit depending on the track (e.g., radius) position of the read head of the CD-ROM device. With the center frequency adjusted close to the data rate of the current track, the phase lock loop circuit needs only a narrow capture band to accurately retrieve the read reference clock from the current track. In one embodiment, the microcontroller is aware of the read head position because it controls read head movement. A microcontroller controlled programmable oscillator (e.g., synthesizer) is used in one embodiment of the novel system to generate the required center frequencies. Direct computation or a look-up table based on the read head position can be used by the microcontroller to determine the required center frequencies. A decoder is supplied with the read reference clock for data decoding.

Data retrieval system and method within a constant angular velocity

Image forming equipment for applying heat to a charged image carrier to attenuate part of the potential of the image carrier in order to form a latent image on the image carrier. The surface of a dielectric image carrier is charged by a charger and a thermal print head is driven in response to image information in order to form a latent image on the charged surface of the image carrier. A developing roller applies a liquid developer to the latent image and presses it against the portion where the potential has been lowered. The resulting toner image formed on the image carrier is fixed on a paper sheet fed from a paper feeding device or is directly fixed on the image carrier. The image carrier is formed of polyethylene terephthalate or a mixture of polybutylene terephthalate and silicon dioxide.

Thermal image forming equipment forms image directly on image carrier or

A developing device for use in an image forming apparatus and having a developing roller, developing sleeve or similar developer carrier for supplying a one-component developer, or toner, to a latent image which is electrostatically formed on an image carrier such as a photoconductive element. A dielectric layer forming part of the developer carrier and closely related to the fluctuation of developing characteristic has a frequency characteristic which is confined in a predetermined range. Hence, the device is operable in a desirable manner by confining the fluctuation of developing characteristic ascribable to that of developing linear speed in a predetermined range without resorting to the actual measurement of a response characteristic of a developer carrier.

Developer carrier with a dielectric layer having a frequency

Growing community of inventors

Tokyo, Japan

Takeo Wada