Sanyo Electric Co., Ltd.

Koji Takano

Fumiaki Nagao

Yuji Kajitani

A method for controlling a stepping motor that moves an object from an initial position by a target distance. The method includes calculating a moved distance of the object, calculating a remaining moving distance of the object, updating a first velocity value until the moved distance exceeds a first reference value, updating a first position value indicating the present position of the accelerated object by adding the updated first velocity value to the first position value, updating a second velocity value when the remaining distance is less than the second reference value by subtracting a second acceleration value from the second velocity value, and updating a second position value indicating the present position of the decelerated object by adding the updated second velocity value to the second position value.

Method for controlling stepping motor

A digital filter is provided with a plurality of selectors. Switchover from one selector to another switches the digital filter operation between a separation filter function and a synthesis filter function. When the digital filter functions as either separation filter or synthesis filter, it switches over between the functions of multiplying data by a filter coefficient and multiplying data by an attenuation coefficient. The entire digital filter circuit size can thus be reduced.

Digital filters

A circuit for controlling the moving of a pickup (track jump) between tracks of a recording medium, such as a CD-ROM. The circuit includes a first circuit which generate a pulse signal corresponding to changing points of a track jump signal and an off track signal. A second circuit generates a signal for controlling the moving speed or deceleration of the pickup, as it approaches a target track, in accordance with the pulse signal.

Method and apparatus for controlling track jump

The processing of a digital filter ( ) switches between the separation of audio data and the synthesis of a plurality of band data. An attenuator ( ), one end of which is connected to the digital filter ( ) and the other end is connected to the audio data input-output port, attenuates the input audio data and supplies it to the digital filter and attenuates and outputs the audio data that has been output from the digital filter ( ). The attenuator ( ) and the digital filter ( ) are commonly used for both data compression and data expansion processing and therefore the entire circuit size of an audio data compression/expansion apparatus is reduced.

Audio data compression/expansion apparatus and digital filter

A tracking servo circuit for stopping movement of a pickup device at a target position on a recording track of a recording medium, such as a CD, includes an A/D converter that generates error data from a tracking signal. The tracking error signal has a positive value when the pickup device is located at a first side of the recording track and a negative value when the pickup device is located on the opposite side of the recording track. The error data includes a code bit indicating the polarity of the tracking signal. A selector control circuit generates a selection signal using the code bit. A selector connected to the A/D converter and the selector control circuit selects either the error data or a fixed data value based on the selection signal. A drive signal generator receives the selected data and generates a drive signal to stop the radial movement of the pickup device.

Tracking servo circuit

A digital filter is provided with a plurality of selectors. Switchover from one selector to another switches the digital filter operation between its separation filter function and synthesis filter function. The digital filter is constructed mainly with a multiplier, an accumulator, and an adder-subtracter which are commonly used to implement both separation and synthesis filters. When the digital filter functions as the separation filter, the input data is output as is to the external by selector switchover.

A separation filter has a memory for storing sequential input data. A multiplier multiplies sequential input data, read from the memory, by a predetermined filter coefficient. An accumulator sequentially accumulates the multiplication result from the multiplier. A pair of registers alternately receive the accumulation result from the accumulator. An adder/subtracter adds or subtracts two accumulation results, obtained from the register pair, together or one from the other, and outputs the operation result as two pieces of sequential output data which are the sequential input data separated. In a synthesizing filter, an adder/subtracter adds or subtracts two pieces of sequential input data together or one from the other, a memory stores the operation result from the adder/subtracter, a multiplier multiplies the operation result, read from the memory, by a predetermined filter coefficient, and an accumulator sequentially accumulates the multiplication result from the multiplier, and outputs the accumulation result as sequential output data which is the two pieces of sequential input data synthesized.

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Ogaki, Japan

Koji Takano