To provide a loudspeaker driving system in which a switch is connected in series to a loudspeaker and a current flowing through the switch is controlled by pulse output from a PWM circuit.
One current terminal of a switch element is connected to one drive terminal of a voice coil in a loudspeaker, a microcomputer is connected to a control terminal of the switch element, one of another drive terminal of the voice coil and another current terminal of the switch element is connected to a ground terminal of a circuit, and the other terminal is connected to a power supply terminal. The microcomputer controls a duty ratio of a pulse signal through a PWM circuit and includes a data processing unit in which, in accordance with the duty ratio of the pulse signal outputted from the PWM circuit, a switch control signal for causing a current to flow to the switch element is outputted from an output circuit to the control terminal. The data processing unit defines the duty ratio of the pulse signal under silence as a first value and, in accordance with sound to be generated, controls the PWM circuit so as to vary the duty ratio of the pulse signal around the first value.
| JP2001196900 | WAVE SHAPING CIRCUIT |
| JPH10241366 | SEMICONDUCTOR INTEGRATED CIRCUIT DEVICE |
| JP2598148 | [Title of Invention] Output circuit |
MATSUSHIMA TADASHI
TAMAKI TOSHIYA
Next Patent: CONTROLLER FOR INDUSTRIAL EQUIPMENT